Society for Ambulatory Assessment

Third quarter 2009 (July to September)

Ad N, Henry L, Hunt S, Barnett S, Stone L. (Jul 2009). The Cox-Maze III procedure success rate: comparison by electrocardiogram, 24-hour holter monitoring and long-term monitoring. Ann Thorac Surg, 88(1), 101-5

BACKGROUND: The detection of atrial arrhythmia recurrence is more accurate when using long-term (5 days to 3 weeks) continuous monitoring devices. In this study, we focus on the comparison of the recurrence of atrial arrhythmias in patients after the Cox-Maze III procedure obtained by three modalities: electrocardiography (ECG), 24-hour Holter monitoring, and long-term monitoring (LTM). METHODS: Patients with follow-up longer than 6 months who reported sinus rhythm while not taking antiarrhythmic drugs were eligible. Atrial arrhythmias longer than 30 s were considered a recurrence. The ECG, 24-hour Holter monitoring, and LTM (5 days) reports were ascertained and compared at the same time. RESULTS: Patients (n = 291) underwent the full Cox-Maze III procedure, with 194 eligible for the study and 76 agreeing to participate. The average time to monitoring after surgery was 9.8 (+/- 7.7) months. The ECGs determined 96% of patients in sinus rhythm, Holter monitoring determined 91% in sinus rhythm, and LTM indicated 84% in sinus rhythm. Comparing ECG results and LTM results revealed that 9 patients (12%) had a significant rhythm change. Holter monitoring did not capture all the patients having events lasting longer than 1 hour. No additional information was captured by the use of LTM in patients with paroxysmal atrial fibrillation. CONCLUSIONS: This study reconfirmed that ECG overestimated the success rate after the Cox-Maze III operation by 12% compared with LTM. These changes may carry clinical significance when determining the success of the Cox-Maze III procedure and determining the medical management, including antiarrhythmic and anticoagulation therapy, of the patients who were found to have significant events.

Adams P, Abela JR, Auerbach R, Skitch S. (Aug 2009). Self-Criticism, Dependency, and Stress Reactivity: An Experience Sampling Approach to Testing Blatt and Zuroff’s (1992) Theory of Personality Predispositions to Depression in High-Risk Youth. Pers Soc Psychol Bull, 35(11),1440-51

S. J. Blatt and D. C. Zuroff’s 1992 theory of personality predispositions to depression posits that individuals who possess high levels of self-criticism and/or dependency are vulnerable to developing depression following negative events. The current study used experience sampling methodology to test this theory in a sample of 49 children ages 7 to 14. Children completed measures of dependency, self-criticism, and depressive symptoms. Subsequently, children were given a handheld computer that signaled them to complete measures of depressive symptoms and negative events at randomly selected times over 2 months. Results of hierarchical linear modeling analyses indicated that higher levels of both self-criticism and dependency were associated with greater elevations in depressive symptoms following negative events. Furthermore, each personality predisposition remained a significant predictor of such elevations after controlling for the interaction between the other personality predisposition and negative events. The results suggest that dependency and self-criticism represent distinct vulnerability factors to depression in youth.

Barta WD, Kurth ME, Stein MD, Tennen H, Kiene SM. (Sep 2009). Craving and self-efficacy in the first five weeks of methadone maintenance therapy: a daily process study. J Stud Alcohol Drugs, 70(5), 735-40

OBJECTIVE: Among individuals initiating methadone maintenance therapy for heroin addiction, low craving and high self-efficacy are thought to predict treatment response; however, in the case of craving, findings have been inconsistent. This study will test two hypotheses: (1) craving and self-efficacy both predict treatment response and (2) withdrawal symptoms and sleep quality predict greater craving and greater self-efficacy, respectively. METHOD: An exploratory study using electronic diary data and multilevel models examined these hypotheses. A sample of 21 heroin users was recruited during the first 1-2 days of methadone maintenance therapy to take part in a 5-week diary study. Comparisons were made between days before participants reached a 70 mg or greater dose and subsequent days. This is in keeping with research showing that this dosage corresponds to optimal opioid receptor blockade. RESULTS: Analysis of 449 diary records nested within 21 participants showed a marked decline in heroin use on days subsequent to the 70 mg methadone dosage plateau. Controlling for methadone dosage plateau, the likelihood of heroin use was lower on days in which participants reported both high self-efficacy and low craving, as compared with other days. Support was found for hypothesized direct associations between craving and withdrawal symptoms and between self-efficacy and sleep quality. CONCLUSIONS: Consistent with a previously published theory, the effect of low craving on positive response to methadone maintenance therapy is evident on days distinguished by high self-efficacy. Also, improving patients’ sleep quality may enhance the benefits of methadone maintenance therapy.

Ben-Zeev D, Young MA, Madsen JW. (Aug 2009). Retrospective recall of affect in clinically depressed individuals and controls. Cognition and Emotion, 23(5), 1021-1040

The current study examined the nature of retrospective recall of affect in depressed participants and nonclinical controls. Utilizing the Experience Sampling Method, we compared average momentary affect reports to retrospective summaries of the same period of time. Both groups exhibited exaggerated retrospective summaries of positive affect (PA) and negative affect (NA). Greater bias for PA than NA was found in the controls but not the depressed. Across groups, depressed individuals exhibited more absolute inaccuracy in their recall of NA but not PA. For depressed and nonclinical individuals, retrospective summaries of PA were better predicted by an average of all weekly momentary PA than a combination of the most intense (“peak”) PA and most recent (“end”) PA experiences. For nonclinical participants, retrospective NA was better predicted by an average of all weekly momentary NA. For depressed individuals, however, no clear advantage to predicting retrospective NA by average weekly NA relative to a combination of peak NA and end NA was found. Based on our findings, clinicians should realize that depressive cognition may not lie in recall that is less positive and more negative than “reality” but in retrospective intensifications of all affect that are, compared to normal, relatively greater for negative than for positive affect.

Bharathi AV, Kuriyan R, Kurpad AV, Thomas T, Ebrahim S, Kinra S, Lyngdoh T, Reddy SK, Dorairaj P, Vaz M. (Aug 2009). Assessment of physical activity using accelerometry, an activity diary, the heart rate method and the Indian Migration Study questionnaire in South Indian adults. Public Health Nutr. [Epub ahead of print]

OBJECTIVE: To validate questionnaire-based physical activity level (PAL) against accelerometry and a 24 h physical activity diary (24 h AD) as reference methods (Protocol 2), after validating these reference methods against the heart rate-oxygen consumption (HRVO2) method (Protocol 1). DESIGN: Cross-sectional study. SETTING: Two villages in Andhra Pradesh state and Bangalore city, South India. SUBJECTS: Ninety-four participants (fifty males, forty-four females) for Protocol 2; thirteen males for Protocol 1. RESULTS: In Protocol 2, mean PAL derived from the questionnaire (1.72 (sd 0.20)) was comparable to that from the 24 h AD (1.78 (sd 0.20)) but significantly higher than the mean PAL derived from accelerometry (1.36 (sd 0.20); P < 0.001). Mean bias of PAL from the questionnaire was larger against the accelerometer (0.36) than against the 24 h AD (-0.06), but with large limits of agreement against both. Correlations of PAL from the questionnaire with that of the accelerometer (r = 0.28; P = 0.01) and the 24 h AD (r = 0.30; P = 0.006) were modest. In Protocol 1, mean PAL from the 24 h AD (1.65 (sd 0.18)) was comparable, while that from the accelerometer (1.51 (sd 0.23)) was significantly lower (P < 0.001), than mean PAL obtained from the HRVO2 method (1.69 (sd 0.21)). CONCLUSIONS: The questionnaire showed acceptable validity with the reference methods in a group with a wide range of physical activity levels. The accelerometer underestimated PAL in comparison with the HRVO2 method.

Björling EA (Sep 2009). The momentary relationship between stress and headaches in adolescent girls. Headache, 49(8), 1186-97

OBJECTIVE: The objective of this study was to compare the relationship between repeated momentary reports of stress and headaches in female adolescents with varying degrees of headache frequency. BACKGROUND: Headaches are the most common form of pain reported by adolescents affecting more than a third of all adolescents. High levels of stress during adolescence may predispose an adolescent to experience headaches in adulthood. Randomized, momentary data collection of stress and headaches provides the most accurate data regarding the adolescent experience of these variables. METHODS: The research methodology, ecological momentary assessment, is a valid approach to better understand the relationship between stress and headaches in adolescence. Data were obtained by each participant’s use of an electronic diary (ED), which captured repeated momentary reports of perceived stress, head pain, and stress-related symptoms in female adolescents with varying degrees of recurrent headache. Seven times per day for the 21-day study period, teen girls responded to ED questions about their current stress levels, head pain, and stress-related symptoms. Based on participants’ momentary reports of headaches, Low Headache, Moderate Headache, and Chronic Headache groups were created. General estimating equation models were used to analyze the relationship between momentary variables as well as the lag effect between stress and head pain. RESULTS: Thirty-one participants, aged 14-18 years, completed 2841 randomized ED reports and reported 674 occurrences of headache. The Chronic Headache and Moderate Headache groups reported significantly increased levels of stress, head pain, and headaches. The relationship between momentary stress and head pain was significantly strong both within and across participants. The strength of this relationship increased with increased headache activity. A significant lag effect was found between stress and headaches; however, the effect of depression as a moderator of the stress and headache relationship remains unclear. CONCLUSION: Perceived stress and head pain was highly correlated in these female adolescents. Given the large population of teens affected by headaches, a plausible next step would be to validate these results in other samples and to determine methods with which to identify teens who may be at risk for a pattern of increasing stress and headaches.

Cain AE, Depp CA, Jeste DV. (Jul 2009). Ecological momentary assessment in aging research: a critical review. J Psychiatr Res, 43(11), 987-96

Ecological momentary assessment (EMA) gathers respondent data on affective, behavioral, and contextual experiences as close in time to those experiences as possible. Potential advantages of EMA in aging research include reducing memory biases and gathering intra-individual data, yet there is little understanding about implementation. The goal of this critical review was to assess the feasibility and applications of EMA in psychological and behavioral research on aging. Through a comprehensive search of the online electronic databases, Psycinfo and Pubmed, for English-language peer-reviewed journals published between 1990 and 2007, we identified 40 articles using EMA methods in older adults. Studies sampled participants between five times per day over one day to once a week for 210 days. Samples were generally not cognitively impaired, evenly split between healthy and clinical populations, and only 6 of 40 studies focused on psychiatric diagnoses. The most common assessment content solicited ratings on affect (n=15), activities of daily living (n=12), physical activities (n=10), and social exchanges (n=8). A total of 90% of the studies that reported compliance reported rates over 80%. Uses of EMA varied widely, with research goals including validation of global measures, detection of subtle treatment effects, and for testing hypotheses about causal intra-individual relationships. Although these measures appear feasible and useful in aging research, recommendations for future studies include adapting measures to enable data collection among older participants with cognitive impairments and/or psychopathology, along with greater use of electronic data capture to improve compliance and increase ease of implementation.

Carpenter MJ,  Saladin ME, DeSantis S, Gray KM, LaRowe SD, Upadhyaya HP. (Jun-Jul 2009). Laboratory-based, cue-elicited craving and cue reactivity as predictors of naturally occurring smoking behavior. Addictive Behaviors, 34(6-7), 536-541

Cigarette craving, one hallmark sign of nicotine dependence, is often measured in laboratory settings using cue reactivity methods. How lab measures of cue reactivity relate to real world smoking behavior is unclear, particularly among non-treatment seeking smokers. Within a larger study of hormonal effects on cue reactivity (N = 78), we examined the predictive relationship of cue reactivity to smoking, each measured in several ways. Results indicated that cue-evoked craving in response to stressful imagery, and to a lesser extent, in vivo smoking cues, significantly predicted smoking behavior during the week following testing. However, this predictive relationship was absent upon controlling for reactivity to neutral cues. Nicotine dependence may moderate the relationship between cue reactivity and actual smoking, such that this predictive relationship is less robust among highly dependent smokers than among smokers low in nicotine dependence. The question of whether cue-elicited craving predicts smoking among smokers not in treatment is best answered with a qualified yes, depending on how craving is manipulated and measured. Our findings highlight important methodological and theoretical considerations for cue reactivity research.

Chastin SF, Dall PM, Tigbe WW, Grant MP, Ryan CG, Rafferty D, Granat MH. (Aug 2009). Compliance with physical activity guidelines in a group of UK-based postal workers using an objective monitoring technique. Eur J Appl Physiol, 106(6), 893-9

Compliance with physical activity (PA) recommendations was assessed using objective PA monitoring of ambulatory activity, in two healthy groups of individuals with active and sedentary occupations. The study showed generally low compliance with the guidelines (53% with 10,000 steps a day; 10% with 30 min of moderate activity a day; and 1% with 30 min of moderate activity a day in bouts of at least 10 min (ACSM)). Adherence to guidelines decreased as more rigorous conditions were applied to the PA data. Use of an objective monitor revealed that health enhancing bouts of activity were performed in periods of approximately 1-min duration, which may be due to unavoidable environmental interruptions. These bouts of activity are much shorter than those advocated in the ACSM guidelines, raising questions regarding how actual behaviour, based on objective monitoring, can be reconciled with guidelines based on self-reported PA.

Chen Z, Brown EN, Barbieri R. (Jul 2009). Assessment of autonomic control and respiratory sinus arrhythmia using point process models of human heart beat dynamics. IEEE Trans Biomed Eng, 56(7), 1791-802

Tracking the autonomic control and respiratory sinus arrhythmia (RSA) from electrocardiogram and respiratory measurements is an important problem in cardiovascular control. We propose a point process adaptive filter algorithm based on an inverse Gaussian model to track heart beat intervals that incorporates respiratory measurements as a covariate and provides an analytic form for computing a dynamic estimate of RSA gain. We use Kolmogorov-Smirnov tests and autocorrelation function analyses to assess model goodness-of-fit. We illustrate the properties of the new dynamic estimate of RSA in the analysis of simulated heart beat data and actual heart beat data recorded from subjects in a four-state postural study of heart beat dynamics: control, sympathetic blockade, parasympathetic blockade, and combined sympathetic and parasympathetic blockade. In addition to giving an accurate description of the heart beat data, our adaptive filter algorithm confirms established findings pointing at a vagally mediated RSA and provides a new dynamic RSA estimate that can be used to track cardiovascular control between and within a broad range of postural, pharmacological, and age conditions. Our paradigm suggests a possible framework for designing a device for ambulatory monitoring and assessment of autonomic control in both laboratory research and clinical practice.

Christensen A, Osterberg LG, Hansen EH. (Aug 2009). Electronic monitoring of patient adherence to oral antihypertensive medical treatment: a systematic review. J Hypertens, 27(8), 1540-51

Poor patient adherence is often the reason for suboptimal blood pressure control. Electronic monitoring is one method of assessing adherence. The aim was to systematically review the literature on electronic monitoring of patient adherence to self-administered oral antihypertensive medications. We searched the Pubmed, Embase, Cinahl and Psychinfo databases and websites of suppliers of electronic monitoring devices. The quality of the studies was assessed according to the quality criteria proposed by Haynes et al. Sixty-two articles were included; three met the criteria proposed by Haynes et al. and nine reported the use of electronic adherence monitoring for feedback interventions. Adherence rates were generally high, whereas average study quality was low with a recent tendency towards improved quality. One study detected investigator fraud based on electronic monitoring data. Use of electronic monitoring of patient adherence according to the quality criteria proposed by Haynes et al. has been rather limited during the past two decades. Electronic monitoring has mainly been used as a measurement tool, but it seems to have the potential to significantly improve blood pressure control as well and should be used more widely.

Cliff DP, Reilly JJ, Okely AD. (Sep 2009). Methodological considerations in using accelerometers to assess habitual physical activity in children aged 0-5 years. J Sci Med Sport, 12(5), 557-67

This paper reviews the evidence behind the methodological decisions accelerometer users make when assessing habitual physical activity in children aged 0-5 years. The purpose of the review is to outline an evidence-guided protocol for using accelerometry in young children and to identify gaps in the evidence base where further investigation is required. Studies evaluating accelerometry methodologies in young children were reviewed in two age groups (0-2 years and 3-5 years) to examine: (i) which accelerometer should be used, (ii) where the accelerometer should be placed, (iii) which epoch should be used, (iv) how many days of monitoring are required, (v) how many minutes of monitoring per day are required, (vi) how data should be reduced, (vii) which cut-point definitions for identifying activity intensity should be used, and (viii) which physical activity outcomes should be reported and how. Critique of the available evidence provided a basis for the development of a recommended users protocol in 3-5-year olds, although several issues require further research. Because of the absence of methodological studies in children under 3 years, a protocol for the use of accelerometers in this age range could not be specified. Formative studies examining the utility, feasibility and validity of accelerometer-based physical activity assessments are required in children under 3 years of age. Recommendations for further research are outlined, based on the above findings, which, if undertaken, will enhance the accuracy of accelerometer-based assessments of habitual physical activity in young children.

Daniel KD, Kim GY, Vassiliou CC, Galindo M, Guimaraes AR, Weissleder R, Charest A, Langer R, Cima MJ. (Jul 2009). Implantable diagnostic device for cancer monitoring. Biosens Bioelectron, 24(11), 3252-7

Biopsies provide required information to diagnose cancer but, because of their invasiveness, they are difficult to use for managing cancer therapy. The ability to repeatedly sample the local environment for tumor biomarker, chemotherapeutic agent, and tumor metabolite concentrations could improve early detection of metastasis and personalized therapy. Here we describe an implantable diagnostic device that senses the local in vivo environment. This device, which could be left behind during biopsy, uses a semi-permeable membrane to contain nanoparticle magnetic relaxation switches. A cell line secreting a model cancer biomarker produced ectopic tumors in mice. The transverse relaxation time (T(2)) of devices in tumor-bearing mice was 20+/-10% lower than devices in control mice after 1 day by magnetic resonance imaging (p<0.01). Short term applications for this device are numerous, including verification of successful tumor resection. This may represent the first continuous monitoring device for soluble cancer biomarkers in vivo.

Dellava JE, Hoffman DJ. (Jul 2009). Validity of resting energy expenditure estimated by an activity monitor compared to indirect calorimetry. Br J Nutr, 102(1), 155-9

The use of activity monitors (triaxial accelerometers) to estimate total energy expenditure in kilocalories is dependent on the estimation of resting energy expenditure (REE). However, the REE estimated by activity monitors has not been validated against more precise techniques, such as indirect calorimetry (IC). Therefore, the objective of the present study was to compare REE estimated by the Actical activity monitor (ActMon) to that measured by IC and standard prediction equations of REE. Fifty healthy adults between 18 and 43 years of age were measured for weight and percentage of body fat using a digital scale and bioelectrical impedance. The REE estimated by the ActMon was only 129 kJ/d higher, but not statistically different (P>0.05), than the REE measured with IC. Using multiple linear regression, there was a positive relationship for men, but not for women, between fat mass (kg) and percentage of body fat and the difference in REE estimated by the ActMon compared to IC (P < 0.001). Therefore, in the cohort studied, the use of an activity monitor to estimate REE is valid when compared to IC, but not to a standard prediction equation of REE.

Desantis AS, Adam EK, Mendelsohn KA, Doane LD. (Jul 2009). Concordance between Self-Reported and Objective Wakeup Times in Ambulatory Salivary Cortisol Research. Int J Behav Med

BACKGROUND: Hypothalamic-pituitary-adrenal (HPA) axis functioning has implications for physical and mental health. One important indicator of HPA axis functioning, the salivary cortisol awakening response (CAR), is sensitive to whether participants provide their samples at the requested times after waking. PURPOSE: To examine the extent to which adolescents report morning wakeup times accurately, test the impact of inaccurate waketime reporting on compliance with a salivary cortisol sampling protocol designed to estimate the CAR, and to examine the implications of non-compliance for CAR estimates. METHOD: In a sample of 91 late adolescents, objective waketimes determined using actigraphy were compared to self-reported waketimes. Associations between accuracy of waketimes and compliance with requested morning cortisol sampling timings (wakeup and 30 min post-awakening) were examined, as were implications of non-compliance for the size of the CAR. RESULTS: In terms of accuracy, 72% of self-reported waketimes were within 5 min and 90% were within 15 min of objective waketimes. Individuals who were more than 5 min discrepant in their waketime reporting, however, had a 90% decrease in their likelihood of being compliant-taking both morning cortisol samples within the requested time frames after waking. However, CARs were significantly lower only among individuals whose subjective and objective waketimes differed by more than 15 min. CONCLUSIONS: Self-reported waketimes were reasonably accurate when compared to objective estimates of time of waking. When available, however, estimates of compliance are improved by knowledge of objective waketimes, resulting in increased accuracy of CAR estimates.

Dollman J, Okely AD, Hardy L, Timperio A, Salmon J, Hills AP. (Sep 2009). A hitchhiker’s guide to assessing young people’s physical activity: Deciding what method to use. J Sci Med Sport, 12(5), 518-25

Researchers and practitioners interested in assessing physical activity in children are often faced with the dilemma of what instrument to use. While there is a plethora of physical activity instruments to choose from, there is currently no guide regarding the suitability of common assessment instruments. The purpose of this paper is to provide a user’s guide for selecting physical activity assessment instruments appropriate for use with children and adolescents. While recommendations regarding specific instruments are not provided, the guide offers information about key attributes and considerations for the use of eight physical activity assessment approaches: heart rate monitoring; accelerometry; pedometry; direct observation; self-report; parent report; teacher report; and diaries/logs. Attributes of instruments and other factors to be considered in the selection of assessment instruments include: population (age); sample size; respondent burden; method/delivery mode; assessment time frame; physical activity information required (data output); data management; measurement error; cost (instrument and administration) and other limitations. A decision flow chart has been developed to assist researchers and practitioners to select an appropriate method of assessing physical activity. Five real-life scenarios are presented to illustrate this process in light of key instrument attributes. It is important that researchers, practitioners and policy makers understand the strengths and limitations of different methods of assessing physical activity, and are guided on selection of the most appropriate instrument/s to suit their needs.

Engel SG, Kahler KA, Lystad CM, Crosby RD, Simonich HK, Wonderlich SA, Peterson CB, Mitchell JE. (Jul 2009). Eating behavior in obese BED, obese non-BED, and non-obese control participants: a naturalistic study. Behav Res Ther, 47(10), 897-900

Laboratory studies have shown considerable differences between the eating behavior, particularly binge eating behavior, of participants with and without binge eating disorder (BED). However, these findings were not replicated in two field experiments employing ecological momentary assessment (EMA) in which obese BED and obese non-BED participants reported comparable binge eating behavior. In the current study, we examined differences in binge eating with an innovative assessment scheme employing both EMA and a standardized computer-based dietary recall program to avoid some of the limitations of past laboratory and field research. Obese BED, obese non-BED, and non-obese control participants reported significant differences in eating patterns, loss of control, overeating, and binge eating behavior. Of particular importance was the finding that BED participants engaged in more overeating and more binge eating episodes than non-BED participants. These findings suggest that the use of EMA in combination with dietary recall may be a relatively objective and useful approach to assessing binge eating behavior. The findings further suggest that individuals with BED are observably different from those without the disorder, which may have implications for eating disorder diagnoses in DSM-V.

Foo MD, Uy MA, Baron RA. (Jul 2009). How do feelings influence effort? An empirical study of entrepreneurs’ affect and venture effort. J Appl Psychol, 94(4),  1086-94

How do feelings influence the effort of entrepreneurs? To obtain data on this issue, the authors implemented experience sampling methodology in which 46 entrepreneurs used cell phones to provide reports on their affect, future temporal focus, and venture effort twice daily for 24 days. Drawing on the affect-as-information theory, the study found that entrepreneurs’ negative affect directly predicts entrepreneurs’ effort toward tasks that are required immediately. Results were consistent for within-day and next-day time lags. Extending the theory, the study found that positive affect predicts venture effort beyond what is immediately required and that this relationship is mediated by future temporal focus. The mediating effects were significant only for next-day outcomes. Implications of findings on the nature of the affect-effort relationship for different time lags are discussed.

Friedman O, Shukla Y, Logan AG. (Sep 2009). Relationship Between Self-Reported Sleep Duration and Changes in Circadian Blood Pressure. Am J Hypertens  [Epub ahead of print]

BackgroundAbnormalities in sleep duration and circadian blood pressure (BP) rhythm are both independently associated with increased risk of death and cardiovascular disease. The relationship, however, between these two entities remains unclear. This study was undertaken to determine whether abnormal sleep duration is associated with nondipping status and elevated morning surge.MethodsIn a cross-sectional study, we assessed the relationship between self-reported sleep duration and circadian BP profiles from 24-h ambulatory BP monitoring (ABPM) in 108 normotensive and 417 hypertensive subjects, independent of relevant sociodemographic, anthropometric, and medical factors.ResultsOn average, subjects reported sleeping 6.5 +/- 1.7 h with 18.5% sleeping </=5 h and 7.6%, >/=9 h. There were 199 (37.9%) nondippers in our cohort and the mean morning surge was 18.7 +/- 1.7 mm Hg. The adjusted odds ratio for nondipping (<10% nocturnal systolic BP fall) associated with a 1-h decrement in sleep duration was 1.12 (P = 0.04) and with age per 5-year increment, 1.15 (P = 0.0003). The adjusted odds ratio for an elevated morning surge (>/=18.0 mm Hg) associated with a 1-h increment in sleep duration was 1.13 (P = 0.02).ConclusionsOur study indicates that a sleep deficit is associated with nondipping and a decreased morning surge, whereas a sleep surfeit is associated with less nondipping and an increased morning surge. These findings provide a possible link for the heightened risk of cardiovascular disease associated with disturbances in circadian BP rhythm and the extremes of sleep quantity.

Fukuo W, Yoshiuchi K, Ohashi K, Togashi H, Sekine R, Kikuchi H, Sakamoto N, Inada S, Sato F, Kadowaki T, Akabayashi A. (Jul 2009). Development of a hand-held personal digital assistant-based food diary with food photographs for Japanese subjects. J Am Diet Assoc, 109(7), 1232-6

Hand-held personal digital assistant (PDA)-based food diaries have been developed for self-monitoring of dietary intake, but the accuracy of these diaries is unclear for patients with diabetes. The aim of the study was to assess the accuracy and feasibility of use of a new PDA-based food diary, including food photographs. The study included 44 Japanese participants without diabetes (mean age 23 years) and 16 Japanese patients with type 2 diabetes (mean age 53 years). The PDA-based food diary was used for 7 consecutive days. Information about all dietary intake on the 7th day of PDA self-monitoring was collected by a 24-hour recall interview on the 8th day. The PDA-based data for dietary intake on the 7th day were then compared to the 24-hour recall data for the same period. Feasibility was assessed based on the frequency and timeliness of self-monitoring. There was no significant difference in daily totals for energy, protein, carbohydrate, and fat between the two methods in each group. Pearson’s correlation and intraclass correlation coefficients showed strong significant relationships for all variables between the two methods in both groups. Bland-Altman plots did not indicate any bias in estimated daily caloric intake. Participants recorded 98% of their meals in the PDA, with 75% of entries recorded within 6 hours after the meal starting time. The findings suggest that the PDA-based food diary is a potential clinical method to estimate dietary intake and may be a beneficial tool for self-monitoring of dietary intake.

Godfrey A, Conway R, Leonard M, Meagher D, Olaighin G. (Aug 2009). A classification system for delirium subtyping with the use of a commercial mobility monitor. Gait Posture, 30(2), 245-52

The usefulness of motor subtypes of delirium is unclear due to inconsistency in subtyping methods and a lack of validation with objective measures of activity. The activity of 40 patients was measured over 24h with a commercial accelerometer-based activity monitor. Accelerometry data from patients with DSM-IV delirium that were readily divided into hyperactive, hypoactive and mixed motor subtypes, were used to create classification trees that were subsequently applied to the remaining cohort to define motoric subtypes. The classification trees used the periods of sitting/lying, standing, stepping and number of postural transitions as measured by the activity monitor as determining factors from which to classify the delirious cohort. The use of a classification system shows how delirium subtypes can be categorised in relation to overall activity and postural changes, which was one of the most discriminating measures examined. The classification system was also implemented to successfully define other patient motoric subtypes. Motor subtypes of delirium defined by observed ward behaviour differ in electronically measured activity levels.

Gorelick ML, Bizzini M, Maffiuletti NA, Munzinger JP, Munzinger U. (Jul 2009). Test-retest reliability of the IDEEA system in the quantification of step parameters during walking and stair climbing. Clin Physiol Funct Imaging, 29(4), 271-6

The aim of this investigation was to evaluate the inter- and intra-session reliability of spatio-temporal gait variables collected during walking and stair climbing with the Intelligent Device for Energy Expenditure and physical Activity (IDEEA) accelerometer-based system. Eighteen healthy subjects (10 men, 8 women) completed a standardized indoor circuit comprised of walking and stair climbing. Intra-and inter-session reliability was investigated for several pertinent spatio-temporal gait variables using intraclass correlations [ICC (3,1)]. Intra-session reliability during walking showed a high reliability of the IDEEA with ICCs ranging between 0.84 (number of steps) and 0.97 (single limb support/double limb support). The ICCs for stair climbing were slightly lower than those during walking with values ranging between 0.74 (step duration) and 0.92 (number of steps). Inter-session reliability during walking showed a high reliability of the IDEEA between all trials, with values ranging between 0.87 (speed) to 0.98 (step duration). The ICCs of stair climbing were again lower than those during walking with values ranging from 0.64 (swing duration) to 0.79 (number of steps). The IDEEA accelerometer-based system provided a highly reliable measurement of spatio-temporal variables, in healthy subjects, during walking with moderately reduced correlations during stair climbing.

Halsey LG, Green JA, Wilson RP, Frappell PB. (Jul 2009). Accelerometry to Estimate Energy Expenditure during Activity: Best Practice with Data Loggers. Physiol Biochem Zool, 82(4), 396-404

Measurement of acceleration can be a proxy for energy expenditure during movement. The variable overall dynamic body acceleration (ODBA), used in recent studies, combines the dynamic elements of acceleration recorded in all three dimensions to measure acceleration and hence energy expenditure due to body movement. However, the simplicity of ODBA affords it limitations. Furthermore, while accelerometry data loggers enable measures to be stored, recording at high frequencies represents a limit to deployment periods as a result of logger memory and/or battery exhaustion. Using bantam chickens walking at different speeds in a respirometer while wearing an accelerometer logger, we investigated the best proxies for rate of oxygen consumption (Vo(2)) from a range of different models using acceleration. We also investigated the effects of sampling acceleration at different frequencies. The best predictor of Vo(2) was a multiple regression including individual measures of dynamic acceleration in each of the three dimensions. However, R(2) was relatively high for ODBA as well and also for certain measures of dynamic acceleration in single dimensions. The aforementioned are single variables, therefore easily derived onboard a data logger and from which a simple calibration equation can be derived. For calibrations of Vo(2) against ODBA, R(2) was consistent as sampling number decreased down to 600 samples of each acceleration channel per ODBA data point, beyond which R(2) tended to be considerably lower. In conclusion, data storage can be maximized when using acceleration as a proxy for Vo(2) by consideration of reductions in (1) number of axes measured and (2) sampling frequency.

Hanlon M, Anderson R. (Sep 2009). Real-time gait event detection using wearable sensors. Gait Posture, 30(4), 523-7

Real-time gait event detection is a requirement for functional electrical stimulation and gait biofeedback. This gait event detection should ideally be achieved using an ambulatory system of durable, lightweight, low-cost sensors. Previous research has reported issues with durability in footswitch systems. Therefore, this study describes the development and assessment of novel detection algorithms using footswitch and accelerometer sensors on 12 healthy individuals. Subjects were equipped with one force sensitive resistor on the heel, one accelerometer at the foot, and one accelerometer at the knee. Subjects performed 10, 8-m walking trials in each of three conditions: normal, slow, and altered (reduced knee ROM) walking. Data from a subset of four subjects were used to develop prediction algorithms for initial contact (IC). Subsequently, these algorithms were tested on the remaining eight subjects against standard forceplate IC data (threshold of 5 N on a rising edge). The footswitch force threshold algorithm was most accurate for IC detection (mean absolute error of 2.4+/-2.1 ms) and was significantly more accurate (p<0.001) than the optimal accelerometer algorithm (mean absolute error of 9.5+/-9.0 ms). The optimal accelerometer algorithm used data from both accelerometers, with IC determined from the second derivative of foot fore-aft acceleration. The error results for footswitch and accelerometer algorithms are lower (approximately 60%) than in previous research o