Imputation of Missing Covariates in Randomized Controlled Trials with Continuous Outcomes: Simple, Unbiased and Efficient Methods

The literature on dealing with missing covariates in nonrandomized studies advocates the use of sophisticated methods like multiple imputation (MI) and maximum likelihood (ML)-based approaches over simple methods. However, these methods are not necessarily optimal in terms of bias and efficiency of treatment effect estimation in randomized studies, where the covariate of interest (treatment group) is independent of all baseline (pre-randomization) covariates due to randomization. This has been shown in the literature, but only for missingness on a single baseline covariate. Here, we extend the situation to multiple baseline covariates with missingness and evaluate the performance of MI and ML compared with simple alternative methods under various missingness scenarios in RCTs with a quantitative outcome. We first derive asymptotic relative efficiencies of the simple methods under the missing completely at random (MCAR) scenario and then perform a simulation study for non-MCAR scenarios. Finally, a trial on chronic low back pain is used to illustrate the implementation of the methods. The results show that all simple methods give unbiased treatment effect estimation but with increased mean squared residual. It also turns out that mean imputation and the missing-indicator method are most efficient under all covariate missingness scenarios and perform at least as well as MI and LM in each scenario.

Sample size calculation and optimal design for regression-based norming of tests and questionnaires

To prevent mistakes in psychological assessment, the precision of test norms is important. This can be achieved by drawing a large normative sample and using regression-based norming. Based on that norming method, a procedure for sample size planning to make inference on Z-scores and percentile rank scores is proposed. Sampling variance formulas for these norm statistics are derived and used to obtain the optimal design, that is, the optimal predictor distribution, for the normative sample, thereby maximizing precision of estimation. This is done under five regression models with a quantitative and a categorical predictor, differing in whether they allow for interaction and nonlinearity. Efficient robust designs are given in case of uncertainty about the regression model. Furthermore, formulas are provided to compute the normative sample size such that individuals' positions relative to the derived norms can be assessed with prespecified power and precision. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Imputation of missing covariate in randomized controlled trials with a continuous outcome: Scoping review and new results

In this article, we first review the literature on dealing with missing values on a covariate in randomized studies and summarize what has been done and what is lacking to date. We then investigate the situation with a continuous outcome and a missing binary covariate in more details through simulations, comparing the performance of multiple imputation (MI) with various simple alternative methods. This is finally extended to the case of time‐to‐event outcome. The simulations consider five different missingness scenarios: missing completely at random (MCAR), at random (MAR) with missingness depending only on the treatment, and missing not at random (MNAR) with missingness depending on the covariate itself (MNAR1), missingness depending on both the treatment and covariate (MNAR2), and missingness depending on the treatment, covariate and their interaction (MNAR3). Here, we distinguish two different cases: (1) when the covariate is measured before randomization (best practice), where only MCAR and MNAR1 are plausible, and (2) when it is measured after randomization but before treatment (which sometimes occurs in nonpharmaceutical research), where the other three missingness mechanisms can also occur. The proposed methods are compared based on the treatment effect estimate and its standard error. The simulation results suggest that the patterns of results are very similar for all missingness scenarios in case (1) and also in case (2) except for MNAR3. Furthermore, in each scenario for continuous outcome, there is at least one simple method that performs at least as well as MI, while for time‐to‐event outcome MI is best.

Factors associated with successful home discharge after inpatient rehabilitation in frail older stroke patients

Background

Stroke is a highly prevalent disease among older people and can have a major impact on daily functioning and quality of life. When community-dwelling older people are hospitalized due to stroke, discharge to an intermediate care facility for geriatric rehabilitation is indicated when return to the previous living situation is expected but not yet possible. However, a substantial proportion is still unable to return home after discharge and has to be admitted to a residential care setting. This study aims to identify which factors are associated with home discharge after inpatient rehabilitation among frail and multimorbid older stroke patients.

Methods

This study is a longitudinal cohort study among 92 community-dwelling stroke patients aged 65 years or over. All patients were admitted to one of eight participating intermediate care facilities for geriatric rehabilitation, under the expectation to return home after rehabilitation. We examined whether 16 potentially relevant factors (age; sex; household situation before admission; stroke history; cardiovascular disorders; diabetes mellitus; multimorbidity; cognitive disability; neglect; apraxia; dysphagia; urinary and bowel incontinence; emotional problems; sitting balance; daily activity level; and independence in activities of daily living) measured at admission were associated with discharge to the former living situation. Logistic regression analysis was used for statistical analysis.

Results

Mean age of the patients was 79.0 years (SD 6.4) and 51.1% was female. A total of 71 patients (77.1%) were discharged to the former living situation within 6 months after the start of geriatric rehabilitation. Of the 16 factors analysed, only a higher level of independence in activities of daily living at admission was significantly associated with home discharge.

Conclusions

Our study shows that the vast majority of previously identified factors predicting home discharge among stroke patients, could not predict home discharge among a group of frail and multimorbid older persons admitted to geriatric rehabilitation. Only a higher level of independence in activities of daily living at admission was significantly related to home discharge. Additional insight in other factors that might predict home discharge after geriatric rehabilitation among this specific group of frail older stroke patients, is needed. Trial registration: ISRCTN ISRCTN62286281. Registered 19-3-2010.

The introduction of the practice nurse mental health in general practices in the Netherlands: effects on number of diagnoses of chronic and acute alcohol abuse

BACKGROUND

Since 2008 mental health practice nurses have been gradually introduced in general practices in the Netherlands as part of health policy aiming to improve early identification and treatment of mental health problems in primary care. This study aims to investigate the effect of the introduction of the practice nurse mental health in general practices in the Netherlands on the number of diagnoses of chronic and acute alcohol abuse.

METHODS

The Netherlands Institute for Health Services Research (NIVEL) retrieved data of a representative sample of general practices (n = 155) for this study. Data were aligned at the starting point of the implementation of the PN-MH to compare the practices on our outcome measures after implementation of the PN-MH. Multilevel regression analyses were conducted to investigate differences in average number of chronic and acute alcohol abuse diagnoses between practices with a practice nurse mental health and control practices (without a practice nurse mental health and without a primary care psychologists).

RESULTS

A significant decrease over time of chronic alcohol abuse diagnoses was observed (ß = -.52, p < 0.05) as well as a significant decrease over time of acute alcohol abuse diagnoses (ß = -.06, p < 0.05). After adjustment for multiple comparisons, no significant differences were found between practices that implemented a practice nurse mental health or only have a primary care psychologist and control practices. Practices that implemented a practice nurse mental health and have a primary care psychologist, had a higher mean of chronic and acute alcohol abuse diagnoses than control practices during all periods, but the differences between these groups were not statistically significant.

CONCLUSIONS

Based on the results of this study it seems that the introduction of practice nurses mental health in general practices is not associated with increased diagnoses of chronic or acute alcohol abuse. Potential explanations are barriers experienced by practice nurses to addressing alcohol use with patients and prioritization of other mental health issues over alcohol abuse. In order to improve the management of alcohol abuse by practice nurses, more research is needed on how practice nurses can be involved in diagnosing and treatment of patients with alcohol abuse.

Relative efficiencies of two-stage sampling schemes for mean estimation in multilevel populations when cluster size is informative

In multilevel populations, there are two types of population means of an outcome variable ie, the average of all individual outcomes ignoring cluster membership and the average of cluster-specific means. To estimate the first mean, individuals can be sampled directly with simple random sampling or with two-stage sampling (TSS), that is, sampling clusters first, and then individuals within the sampled clusters. When cluster size varies in the population, three TSS schemes can be considered, ie, sampling clusters with probability proportional to cluster size and then sampling the same number of individuals per cluster; sampling clusters with equal probability and then sampling the same percentage of individuals per cluster; and sampling clusters with equal probability and then sampling the same number of individuals per cluster. Unbiased estimation of the average of all individual outcomes is discussed under each sampling scheme assuming cluster size to be informative. Furthermore, the three TSS schemes are compared in terms of efficiency with each other and with simple random sampling under the constraint of a fixed total sample size. The relative efficiency of the sampling schemes is shown to vary across different cluster size distributions. However, sampling clusters with probability proportional to size is the most efficient TSS scheme for many cluster size distributions. Model-based and design-based inference are compared and are shown to give similar results. The results are applied to the distribution of high school size in Italy and the distribution of patient list size for general practices in England.

The effectiveness of an integrated care pathway in geriatric rehabilitation among older patients with complex health problems and their informal caregivers: a prospective cohort study

Background

To improve continuity and coordination of care in geriatric rehabilitation, an integrated care pathway was developed and implemented in The Netherlands. The purpose of this study was to assess the effects of this pathway on patients and informal caregivers.

Methods

Two cohorts of patients and their informal caregivers were prospectively recruited before implementation of the pathway (2011–2012) and after implementation of the pathway (2013–2014). Primary outcome measures were dependence in activities of daily living in patients (KATZ-15) and self-rated burden among informal caregivers (SRB-VAS). Secondary outcome measures were the frequency of performing extended daily activities, social participation, psychological well-being, quality of life and discharge location (patients) and quality of life and objective care burden (informal caregivers). Outcomes were measured at baseline, after three and after nine months.

Results

No effect was shown on the KATZ-15 after three and nine months. However, a larger percentage of patients were discharged home in the care pathway cohort (83% vs 58.1% after three months and 88.6% vs 67.4% after nine months; p = 0.004). Furthermore, after three months, patients from the care pathway cohort performed more extended daily activities (p = 0.014) and informal caregivers experienced a lower self-rated burden (p = 0.05). After nine months, these effects disappeared. No differences were found for the other outcome measures.

Conclusions

Due to the positive effects of the integrated care pathway, we are inclined to recommend implementing the care pathway in regular care. To have longer lasting effects among patients and informal caregivers, we suggest actively disseminating information about the pathway to primary care providers who are currently still unaware of its content.

Trial registration

ISRCTN90000867 (date of registration: 07-04-2016).

Professional and family caregivers' attitudes towards involuntary treatment in community-dwelling people with dementia

Aims

The aim of this study was to gain insight into professional and family caregivers’ attitudes towards involuntary treatment in community‐dwelling people with dementia (PwD).

Background

The number of PwD with complex care needs living at home is increasing rapidly. In some situations, caregivers provide care against the will of PwD, referred to as involuntary treatment, which includes non‐consensual care, psychotropic medication and physical restraints.

Design

A cross‐sectional study.

Methods

A total of 228 professional (nursing staff, general practitioners (GPs) and other healthcare professionals such as physical therapists and psychologists) and 77 family caregivers of PwD completed the Maastricht Attitude Questionnaire—Home Care. This questionnaire measures attitudes towards involuntary treatment and perceived restrictiveness of and experienced discomfort in using involuntary treatment. Data were collected in the Netherlands between June and November 2016.

Results

Family caregivers and GPs had more positive attitudes towards involuntary treatment than nursing staff and other healthcare professionals, indicating that they are more accepting of involuntary treatment. A more positive attitude was associated with higher perceived caregiver burden and being a family caregiver. Family caregivers and GPs found the use of involuntary treatment less restrictive and indicated feeling more comfortable when using these measures.

Conclusion

It is important to account for the differences in attitudes and foster dialogue among professional and family caregivers to find common ground about alternatives to involuntary treatment. These results will inform the development of an intervention that aims to prevent involuntary treatment in home care.

The relation between mood, activity, and interaction in long-term dementia care

OBJECTIVE

The aim of the study is to identify the degree of association between mood, activity engagement, activity location, and social interaction during everyday life of people with dementia (PwD) living in long-term care facilities.

METHOD

An observational study using momentary assessments was conducted. For all 115 participants, 84 momentary assessments of mood, engagement in activity, location during activity, and social interaction were carried out by a researcher using the tablet-based Maastricht Electronic Daily Life Observation-tool.

RESULTS

A total of 9660 momentary assessments were completed. The mean age of the 115 participants was 84 and most (75%) were women. A negative, neutral, or positive mood was recorded during 2%, 25%, and 73% of the observations, respectively. Positive mood was associated with engagement in activities, doing activities outside, and social interaction. The type of activity was less important for mood than the fact that PwD were engaged in an activity. Low mood was evident when PwD attempted to have social interaction but received no response.

CONCLUSION

Fulfilling PwD's need for occupation and social interaction is consistent with a person-centred dementia care focus and should have priority in dementia care.

Quality of care and quality of life of people with dementia living at green care farms: a cross-sectional study

BACKGROUND

Many countries are introducing smaller, more home-like care facilities that represent a radically new approach to nursing home care for people with dementia. The green care farm is a new type of nursing home developed in the Netherlands. The goal of this study was to compare quality of care, quality of life and related outcomes in green care farms, regular small-scale living facilities and traditional nursing homes for people with dementia.

METHODS

A cross-sectional design was used. Three types of nursing homes were included: (1) green care farms; (2) regular small-scale living facilities; (3) traditional nursing homes. All participating nursing homes were non-profit, collectively funded nursing homes in the south of the Netherlands. One hundred and fifteen residents with a formal diagnosis of dementia were included in the study. Data on quality of care was gathered and consisted of outcome indicators (e.g. falling incidents, pressure ulcers), structure indicators (e.g. hours per resident per day), and process indicators (e.g. presence, accessibility and content of protocols on care delivery). Furthermore, questionnaires on cognition, dependence in activities of daily living, quality of life, social engagement, neuropsychiatric symptoms, agitation, and depression were used.

RESULTS

Data showed that quality of care was comparable across settings. No large differences were found on clinical outcome measures, hours per resident per day, or process indicators. Higher quality of life scores were reported for residents of green care farms in comparison with residents of traditional nursing homes. They scored significantly higher on the Quality of Life - Alzheimer's disease Scale (p < 0.05, ES = 0.8) indicating a better quality of life. In addition, residents of green care farms scored higher on three quality of life domains of the Qualidem: positive affect, social relations and having something to do (p < 0.05, ES > 0.7). No differences with regular small-scale living facilities were found.

CONCLUSIONS

Green care farms seem to be a valuable alternative to existing nursing homes. This is important as people with dementia are a heterogeneous group with varying needs. In order to provide tailored care there also is a need for a variety of living environments.

Promoting Functional Activity Among Nursing Home Residents: A Cross-Sectional Study on Barriers Experienced by Nursing Staff

OBJECTIVE

To obtain insight into (a) the prevalence of nursing staff-experienced barriers regarding the promotion of functional activity among nursing home residents, and (b) the association between these barriers and nursing staff-perceived promotion of functional activity.

METHOD

Barriers experienced by 368 nurses from 41 nursing homes in the Netherlands were measured with the MAastrIcht Nurses Activity INventory (MAINtAIN)-barriers; perceived promotion of functional activities was measured with the MAINtAIN-behaviors. Descriptive statistics and hierarchical linear regression analyses were performed.

RESULTS

Most often experienced barriers were staffing levels, capabilities of residents, and availability of resources. Barriers that were most strongly associated with the promotion of functional activity were communication within the team, (a lack of) referral to responsibilities, and care routines.

DISCUSSION

Barriers that are most often experienced among nursing staff are not necessarily the barriers that are most strongly associated with nursing staff-perceived promotion of functional activity.

Estimated Glomerular Filtration Rate and Albuminuria Are Associated with Biomarkers of Cardiac Injury in a Population-Based Cohort Study: The Maastricht Study

BACKGROUND

Chronic kidney disease (CKD) is associated with an increased cardiovascular disease mortality risk. It is, however, less clear at what point in the course from normal kidney function to CKD the association with cardiovascular disease appears. Studying the associations of estimated glomerular filtration rate (eGFR) and albuminuria with biomarkers of (subclinical) cardiac injury in a population without substantial CKD may clarify this issue.

METHODS

We examined the cross-sectional associations of eGFR and urinary albumin excretion (UAE) with high-sensitivity cardiac troponin (hs-cTn) T, hs-cTnI, and N-terminal probrain natriuretic-peptide (NT-proBNP) in 3103 individuals from a population-based diabetes-enriched cohort study.

RESULTS

After adjustment for potential confounders, eGFR and UAE were associated with these biomarkers of cardiac injury, even at levels that do not fulfill the CKD criteria. For example, eGFR 60-<90 mL · min^-1 ·(1.73 m²)^-1 [vs ≥90 mL · min^-1 · (1.73 m²)^-1] was associated with a [ratio (95% CI)] 1.21 (1.17-1.26), 1.14 (1.07-1.20), and 1.19 (1.12-1.27) times higher hs-cTnT, hs-cTnI, and NT-proBNP, respectively. The association of eGFR with hs-cTnT was statistically significantly stronger than that with hs-cTnI. In addition, UAE 15-<30 mg/24 h (vs <15 mg/24 h) was associated with a 1.04 (0.98-1.10), 1.08 (1.00-1.18), and 1.07 (0.96-1.18) times higher hs-cTnT, hs-cTnI, and NT-proBNP, respectively.

CONCLUSIONS

eGFR and albuminuria were already associated with biomarkers of (subclinical) cardiac injury at levels that do not fulfill the CKD criteria. Although reduced renal elimination may partly underlie the associations of eGFR, these findings support the concept that eGFR and albuminuria are, over their entire range, associated with cardiac injury.

Pressure Ulcer Prevalence and Care in Indonesian Hospitals: A Multicenter, Cross-sectional Evaluation Using an Extended Donabedian Model

Although the number of studies on pressure ulcer (PU) occurrence continues to grow, research regarding the quality of PU care and its effect on outcomes is limited. Using an extended Donabedian model, a 1-day, multicenter, cross-sectional evaluation of the quality of PU care was conducted in a convenience sample of Indonesian hospitals among patients ≥18 years of age in the medical, surgical, and intensive care units. Structure (ie, hospital attributes), process (recommended PU preventive measures), and outcome indicators (nosocomial PU prevalence excluding nonblanchable erythema), along with patient characteristics (age, gender, ethnicity, admission days, diseases [per ICD-10], recent surgery, PU categorization [4 categories according to National Pressure Ulcer Advisory Panel-European Pressure Ulcer Advisory Panel guidelines], PU history, care dependency, and Braden score) were examined. Patient data were collected by 2 nurses -1 from the patient's unit and 1 from another unit - using the Landelijke Prevalentiemeting Zorgproblemen-International questionnaire, a paper-and-pencil survey translated into Indonesian. Heads of wards and nursing units completed the questionnaires at institutional and ward levels, respectively. The data were analyzed using descriptive and bivariate analyses, and multilevel logistic regression modeling was applied according to the generalized estimating equation approach. Among the 4 participating hospitals, 66 care units, 36 pairs of nurses, and 1132 adult patients (mean age 48.7 ± 17.4 years, 40.9% women) were involved. Ninety-one (91) patients developed 1 or more PUs; the nosocomial PU prevalence (excluding nonblanchable erythema, category I) was 3.6%. The most frequently used PU preventive measures were patient education (329, 29.1%), repositioning (269, 23.8%), and skin moisturizing (266, 23.5%). The factors most associated with nosocomial PU rate excluding category I were the inclusion of PU care in patient care files (P = .001), repositioning (P = .002), skin moisturizing (P = .009), age (P = .013), admission days (P = .001), care dependency scores (P = .047), immobility (P = .001), sensory perception limitation (P = .001), moist skin (P = .032, OR 13.74), and friction and shear problem (P = .001). The prevalence of nosocomial PUs in this study was comparable to previous research in the Netherlands and rather low, even though limited structural indicators and suboptimal preventive measures were noted. Also, outdated preventive measures such as massage, donuts, and water-filled gloves were still used. The quality of PU care in these hospitals may be improved by addressing the absence of structural factors, including protocols/guidelines. Future research is needed for guideline implementation programs in Indonesian hospitals.

Relationship between the presence of baccalaureate-educated RNs and quality of care: a cross-sectional study in Dutch long-term care facilities

BACKGROUND

Recent evidence suggests that an increase in baccalaureate-educated registered nurses (BRNs) leads to better quality of care in hospitals. For geriatric long-term care facilities such as nursing homes, this relationship is less clear. Most studies assessing the relationship between nurse staffing and quality of care in long-term care facilities are US-based, and only a few have focused on the unique contribution of registered nurses. In this study, we focus on BRNs, as they are expected to serve as role models and change agents, while little is known about their unique contribution to quality of care in long-term care facilities.

METHODS

We conducted a cross-sectional study among 282 wards and 6,145 residents from 95 Dutch long-term care facilities. The relationship between the presence of BRNs in wards and quality of care was assessed, controlling for background characteristics, i.e. ward size, and residents' age, gender, length of stay, comorbidities, and care dependency status. Multilevel logistic regression analyses, using a generalized estimating equation approach, were performed.

RESULTS

57% of the wards employed BRNs. In these wards, the BRNs delivered on average 4.8 min of care per resident per day. Among residents living in somatic wards that employed BRNs, the probability of experiencing a fall (odds ratio 1.44; 95% CI 1.06-1.96) and receiving antipsychotic drugs (odds ratio 2.15; 95% CI 1.66-2.78) was higher, whereas the probability of having an indwelling urinary catheter was lower (odds ratio 0.70; 95% CI 0.53-0.91). Among residents living in psychogeriatric wards that employed BRNs, the probability of experiencing a medication incident was lower (odds ratio 0.68; 95% CI 0.49-0.95). For residents from both ward types, the probability of suffering from nosocomial pressure ulcers did not significantly differ for residents in wards employing BRNs.

CONCLUSIONS

In wards that employed BRNs, their mean amount of time spent per resident was low, while quality of care on most wards was acceptable. No consistent evidence was found for a relationship between the presence of BRNs in wards and quality of care outcomes, controlling for background characteristics. Future studies should consider the mediating and moderating role of staffing-related work processes and ward environment characteristics on quality of care.

Work environment characteristics associated with quality of care in Dutch nursing homes: A cross-sectional study

BACKGROUND

A lack of relationship between direct care staffing levels and quality of care, as found in prior studies, underscores the importance of considering the quality of the work environment instead of only considering staff ratios. Only a few studies, however, have combined direct care staffing with work environment characteristics when assessing the relationship with quality of care in nursing homes.

OBJECTIVES

To examine the relationship between direct care staffing levels, work environment characteristics and perceived quality of care in Dutch nursing homes.

DESIGN

Cross-sectional, observational study in cooperation with the Dutch Prevalence Measurement of Care Problems.

SETTINGS

Twenty-four somatic and 31 psychogeriatric wards from 21 nursing homes in the Netherlands.

PARTICIPANTS

Forty-one ward managers and 274 staff members (registered nurses or certified nurse assistants) from the 55 participating wards.

METHODS

Ward rosters were discussed with managers to obtain an insight into direct care staffing levels (i.e, total direct care staff hours per resident per day). Participating staff members completed a questionnaire on work environment characteristics (i.e., ward culture, team climate, communication and coordination, role model availability, and multidisciplinary collaboration) and they rated the quality of care in their ward. Data were analyzed using multilevel linear regression analyses (random intercept). Separate analyses were conducted for somatic and psychogeriatric wards.

RESULTS

In general, staff members were satisfied with the quality of care in their wards. Staff members from psychogeriatric wards scored higher on the statement 'In the event that a family member had to be admitted to a nursing home now, I would recommend this ward'. A better team climate was related to better perceived quality of care in both ward types (p≤0.020). In somatic wards, there was a positive association between multidisciplinary collaboration and agreement by staff of ward recommendation for a family member (p=0.028). In psychogeriatric wards, a lower score on market culture (p=0.019), better communication/coordination (p=0.018) and a higher rating for multidisciplinary collaboration (p=0.003) were significantly associated with a higher grade for overall quality of care. Total direct care staffing, adhocracy culture, hierarchy culture, as well as role model availability were not significantly related to quality of care.

CONCLUSIONS

Our findings suggest that team climate may be an important factor to consider when trying to improve quality of care. Generating more evidence on which work environment characteristics actually lead to better quality of care is needed.

Diurnal Rhythm of Cardiac Troponin: Consequences for the Diagnosis of Acute Myocardial Infarction

BACKGROUND

Interpretation of serial high-sensitivity cardiac troponin (hs-cTn) measurements for the diagnosis of acute myocardial infarction (AMI) assumes random fluctuation of hs-cTn around an individual's homeostatic set point. The aim of this study was to challenge this diagnostic concept.

METHODS

Study 1 examined the presence of a diurnal hs-cTn rhythm by hourly blood sampling, day and night, in 24 individuals without a recent history of AMI. Study 2 assessed morning vs evening diagnostic accuracy of hs-cTnT and hs-cTnI in a prospective multicenter diagnostic study of 2782 unselected patients, presenting to the emergency department with acute chest pain.

RESULTS

In study 1, hs-cTnT, but not hs-cTnI, exhibited a diurnal rhythm, characterized by gradually decreasing concentrations throughout daytime, rising concentrations during nighttime, to peak concentrations in the morning (mean 16.2 ng/L at 8:30 AM and 12.1 ng/L at 7:30 PM). In study 2, the hs-cTnT rhythm was confirmed by higher hs-cTnT concentrations in early-morning presenters compared to evening presenters with an adjudicated diagnosis of noncardiac disease. The diagnostic accuracy [area under the receiver-operation characteristics curve (AUC)] of hs-cTnT at presentation, 1 h, and for the combination of absolute changes with presenting concentration, were very high and comparable among patients presenting early morning as compared to evening (all AUC &gt;0.93). hs-cTnI exhibited no diurnal rhythm with no differences in AUC among early-morning and evening presenters.

CONCLUSIONS

Rhythmic diurnal variation of hs-cTnT is a general phenomenon that is not seen with hs-cTnI. While the diurnal hs-cTnT rhythm does not seem to affect the diagnostic accuracy of hs-cTnT for AMI, it should be considered when using hs-cTnT for screening purposes.

Clinical Trial Registration

1. Circadian Variation of Cardiac Troponin, NCT02091427, www.clinicaltrials.gov/ct2/show/NCT02091427. 2. Advantageous Predictors of Acute Coronary Syndrome Evaluation (APACE) Study, NCT00470587, www.clinicaltrials.gov/ct2/show/NCT00470587.

The Competing Demands of Paid Work and Parent Care

This article investigates the potentially competitive relationship between paid work and parent care provided by daughters and daughters-in-law. In line with the scarcity hypothesis of role theory, four subhypotheses were formulated and tested empirically. In a population-based probability sample of middle-aged women ( n = 581), only partial empirical support was found for the scarcity or role conflict hypothesis. It appeared that employment significantly reduces the chances of becoming a caregiver. However, parent care and employment are not conflicting in time as the amount of care provided to parents was not affected by out-of-home employment. Parent care has only a small impact on work decisions, and employed caregivers do not experience more caregiver role strain. It was hypothesized that employed women not yet providing care anticipate a role conflict when a parent becomes frail and needs help. Consequently, a self-selection process takes place whereby the nearest living daughter with the least competing demands is most likely to accept the caregiver role. Once the caregiver role is accepted, both role strain and the time spent on parent care are determined by factors other than employment status or work hours.

The association between aspects of daily life and quality of life of people with dementia living in long-term care facilities: a momentary assessment study

BACKGROUND

To improve the quality of life (QoL) of people with dementia (PwD) living in long-term care facilities, insight into the association between QoL and how people spend their daily lives is urgently needed. This study investigated which aspects of daily life are related to QoL in dementia.

METHODS

An observational study was conducted. Daily life was assessed with the tablet-based Maastricht Electronic Daily Life Observation-tool (MEDLO-tool). Aspects included activity, engagement in the activity, social interaction, physical effort, mood, and agitation. QoL was assessed by formal nursing caregivers using the Quality of Life-Alzheimer's Disease scale (QoL-AD). A total of 9,660 momentary assessments were conducted.

RESULTS

The mean age of the 115 participants was 84 years and most (75%) were women. Bivariate analyses showed that residents with a higher QoL carried out less passive/purposeless activities (25% vs. 38%), were more engaged in active, expressive, and social activities, (40% vs. 27%), had more social interaction (34% vs. 22%), and had better mood scores (scale 1-7, 5.0 vs. 4.8), compared with residents with a lower QoL (all p-values < 0.001). Multivariate analyses showed that having more social interaction and a positive mood are related to a higher QoL.

CONCLUSIONS

The results underline the importance of social interaction and a positive mood for a higher QoL. Future research should investigate the importance of engagement in activities in more detail.

A Multifactorial Weight Reduction Programme for Children with Overweight and Asthma: A Randomized Controlled Trial

Background

There is increasing evidence that obesity is related to asthma development and severity. However, it is largely unknown whether weight reduction can influence asthma management, especially in children.

Objective

To determine the effects of a multifactorial weight reduction intervention on asthma management in overweight/obese children with (a high risk of developing) asthma.

Methods

An 18-month weight-reduction randomized controlled trial was conducted in 87 children with overweight/obesity and asthma. Every six months, measurements of anthropometry, lung function, lifestyle parameters and inflammatory markers were assessed. Analyses were performed with linear mixed models for longitudinal analyses.

Results

After 18 months, the body mass index-standard deviation score decreased by -0.14±0.29 points (p<0.01) in the intervention group and -0.12±0.34 points (p<0.01) in the control group. This change over time did not differ between groups (p>0.05). Asthma features (including asthma control and asthma-related quality of life) and lung function indices (static and dynamic) improved significantly over time in both groups. The FVC% predicted improved over time by 10.1 ± 8.7% in the intervention group (p<0.001), which was significantly greater than the 6.1 ± 8.4% in the control group (p<0.05).

Conclusions & clinical relevance

Clinically relevant improvements in body weight, lung function and asthma features were found in both the intervention and control group, although some effects were more pronounced in the intervention group (FVC, asthma control, and quality of life). This implies that a weight reduction intervention could be clinically beneficial for children with asthma.

Trial Registration

ClinicalTrials.gov NCT00998413

Heart failure in nursing home residents; a cross-sectional study to determine the prevalence and clinical characteristics

Background

Heart failure (HF) is expected to be highly prevalent in nursing home residents, but precise figures are scarce. The aim of this study was to determine the prevalence of HF in nursing home residents and to get insight in the clinical characteristics of residents with HF.

Methods

The study followed a multi-centre cross-sectional design.

Nursing home residents (n = 501) in the southern part of the Netherlands aged over 65 years and receiving long-term somatic or psychogeriatric care were included in the study. The diagnosis of HF and related characteristics were based on data collected from actual clinical examinations (including history, physical examination, ECG, cardiac markers and echocardiography), patient records and questionnaires. A panel of two cardiologists and a geriatrician ultimately judged the data to diagnose HF.

Results

The overall prevalence of HF in nursing home residents was 33 %, of which 52 % had HF with preserved ejection fraction. The symptoms dyspnoea and oedema and a cardiac history were more common in residents with HF. Diabetes mellitus, chronic obstructive pulmonary disease (COPD) were also more prevalent in those with HF. Residents with HF had a higher score on the Mini Mental State Examination. 54 % of those with HF where not known before, and in 31 % with a history of HF, this diagnosis was not confirmed by the expert panel.

Conclusion

This study shows that HF is highly prevalent in nursing home residents with many unknown or falsely diagnosed with HF. Equal number of HF patients had reduced and preserved left-ventricular ejection fraction.

Trial registration

The Netherlands National Trial Register NTR2663 (27-12-2010)

Living at the farm, innovative nursing home care for people with dementia - study protocol of an observational longitudinal study

Background

In nursing home care, new care environments directed towards small-scale and homelike environments are developing. The green care farm, which provides 24-h nursing home care for people with dementia, is one such new care environment. Knowledge is needed on the relation between environmental features of green care farms such as nature, domesticity and offering care in small groups and the influence on the daily lives of residents. The aim of this study is to explore (1) the daily lives of residents, (2) the quality of care and (3) the experiences of caregivers on green care farms compared with other nursing home care environments.

Methods/design

An observational longitudinal study including a baseline and a six-month follow-up measurement is carried out. Four types of nursing home care environments are included: (1) large scale nursing home ward, (2) small scale living facility on the terrain of a larger nursing home (3) stand-alone small scale living facility and (4) green care farm. Quality of care is examined through structure, process and outcome indicators. The primary outcome measure is the daily life of residents, assessed by ecological momentary assessments. Aspects of daily life include (1) activity (activity performed by the resident, the engagement in this activity and the degree of physical effort); (2) physical environment (the location of the resident and the interaction with the physical environment); (3) social environment (the level and type of social interaction, and with whom this social interaction took place) and (4) psychological well-being (mood and agitation). In addition, social engagement, quality of life, behavioral symptoms and agitation are evaluated through questionnaires. Furthermore, demographics, cognitive impairment, functional dependence and the severity of dementia are assessed. Semi-structured interviews are performed with caregivers regarding their experiences with the different nursing home care environments.

Discussion

This is the first study investigating green care farms providing 24-h nursing home care for people with dementia. The study provides valuable insight into the daily lives of residents, the quality of care, and the experiences of caregivers at green care farms in comparison with other nursing home care environments including small-scale care environments and large scale nursing home wards.

Daily (In)Activities of Nursing Home Residents in Their Wards: An Observation Study

OBJECTIVES

Research shows that nursing home residents are largely inactive. This inactivity negatively influences physical fitness, and participation in daily activities is known to have a positive influence on physical function and quality of life. Existing research does not provide sufficient insight into the daily activities in which nursing home residents participate. This insight is needed to develop future interventions so as to encourage nursing home residents to participate in daily activities and, thereby, decrease inactivity. The purpose of this study was to obtain insight into daily (in)activities of psychogeriatric and somatic nursing home residents during the day and their body positions during these (in)activities.

DESIGN

Cross-sectional observation study.

SETTING

Nursing homes in the Netherlands (19 psychogeriatric and 11 somatic wards).

PARTICIPANTS

Participants were 723 home residents in 7 nursing homes.

MEASUREMENTS

Observations were conducted using a self-developed observation list. Residents were observed in their wards during 5 random observation times between 7:00 am and 11:00 pm, in which the daily activity and position of the resident during this activity were scored. Percentages of activities and positions were calculated for each observation time.

RESULTS

In total, 3282 observations (91% of the intended 3615 observations) were conducted. Nursing home residents of both psychogeriatric and somatic wards were mainly observed partaking in in activities, such as sleeping, doing nothing, and watching TV (range: 45%-77% of the 5 observation times). Furthermore, residents were engaged in activities of daily living (ADLs) (range: 15%-38%) that mainly comprised activities related to mobility (range: 10%-19%) and eating and drinking (range: 2%-17%). Engagement of residents in instrumental ADLs (IADLs) was rarely observed (up to 3%). Residents were largely observed in a lying or sitting position (range: 89%-92%).

CONCLUSION

Most of the psychogeriatric and somatic nursing home residents spend their day inactive in a lying or sitting position in the ward. To encourage nursing home residents in daily activities in the wards, interventions are needed that (1) focus on increasing ADLs and IADLs, and (2) encourage standing and walking.

Growth and endothelial function in the first 2 years of life

OBJECTIVE

To test the hypothesis that the inverse association between infant growth and endothelial function at 6 months would persist to 24 months and that accelerated growth would lead to an increased percent body fat, which would, in turn, impact negatively on endothelial function.

STUDY DESIGN

In a prospective observational study, 104 healthy term newborns underwent anthropometry and measurements of vascular vasodilation at 0, 6, 12, and 24 months. We recorded maximum vasodilation in response to acetylcholine (endothelium-dependent) and nitroprusside (endothelium-independent) by use of laser-Doppler vascular perfusion monitoring of the forearm skin vasculature. Additional anthropometry at 1 and 3 months was collected from child welfare centers. The data were analyzed by multilevel linear regression.

RESULTS

Weight gain from 0-1 month was associated inversely with maximum perfusion in response to acetylcholine at the age of 2 years (b = -8.28 perfusion units [PU] per Δ z-score, P = .03). Weight gain from 0-1 month was related positively to maximum perfusion in response to nitroprusside (b = 10.12 PU per Δ z-score, P = .04), as was birth weight (b = 8.02 PU per z-score, P = .02). Body fat percentage did not have a significant effect in any of the perfusion models and was not related to maximum perfusion at 2 years.

CONCLUSION

Infant weight gain from 0-1 month is inversely related to endothelial function in healthy term infants, at least to the age of 2 years. This relationship was not explained by an increased percentage body fat.

Instruments to assess sarcopenia and physical frailty in older people living in a community (care) setting: similarities and discrepancies

OBJECTIVES

Both sarcopenia and physical frailty are geriatric syndromes causing loss of functionality and independence. This study explored the association between sarcopenia and physical frailty and the overlap of their criteria in older people living in different community (care) settings. Moreover, it investigated the concurrent validity of the FRAIL scale to assess physical frailty, by comparison with the widely used Fried criteria.

DESIGN

Data were retrieved from the cross-sectional Maastricht Sarcopenia Study (MaSS).

SETTING

The study was undertaken in different community care settings in an urban area (Maastricht) in the south of the Netherlands.

PARTICIPANTS

Participants were 65 years or older, gave written informed consent, were able to understand Dutch language, and were not wheelchair bound or bedridden.

INTERVENTION

Not applicable.

MEASUREMENTS

Sarcopenia was identified using the algorithm of the European Working Group on Sarcopenia in Older People. Physical frailty was assessed by the Fried criteria and by the FRAIL scale. Logistic regression was performed to assess the association between sarcopenia and physical frailty measured by the Fried criteria. Spearman correlation was performed to assess the concurrent validity of the FRAIL scale compared with the Fried criteria.

RESULTS

Data from 227 participants, mean age 74.9 years, were analyzed. Sarcopenia was identified in 23.3% of the participants, when using the cutoff levels for moderate sarcopenia. Physical frailty was identified in 8.4% (≥3 Fried criteria) and 9.3% (≥3 FRAIL scale criteria) of the study population. Sarcopenia and physical frailty were significantly associated (P = .022). Frail older people were more likely to be sarcopenic than those who were not frail. In older people who were not frail, the risk of having sarcopenia increased with age. Next to poor grip strength (78.9%) and slow gait speed (89.5%), poor performance in other functional tests was common in frail older people. The 2 physical frailty scales were significantly correlated (r = 0.617, P < .001).

CONCLUSION

Sarcopenia and physical frailty were associated and partly overlap, especially on parameters of impaired physical function. Some evidence for concurrent validity between the FRAIL scale and Fried criteria was found. Future research should elicit the value of combining sarcopenia and frailty measures in preventing disability and other negative health outcomes.

Maternal but not fetal FADS gene variants modify the association between maternal long-chain PUFA intake in pregnancy and birth weight

Several studies have shown a positive association between maternal fish intake in pregnancy and pregnancy duration and child birth weight (BW), probably due to fish n-3 (ω-3) long-chain polyunsaturated fatty acids (LC-PUFAs). n-3 LC-PUFAs can also be synthesized endogenously, and their synthesis depends on single nucleotide polymorphisms (SNPs) in the fatty acid desaturase (FADS) gene encoding for FADS. We assessed the associations of maternal docosahexaenoic acid (DHA) intake in pregnancy with pregnancy duration and BW and investigated whether these associations are modified by maternal or fetal FADS SNP genotypes. We hypothesized that we would find stronger associations in minor allele homozygous mothers or fetuses due to their lower n-3 LC-PUFA endogenous synthesis and hence higher dependence on dietary supply. Data on maternal diet, pregnancy duration, and BW were available for 2622 mother-child pairs from the KOALA (Kind, Ouders en gezondheid: Aandacht voor Leefstijl en Aanleg) Birth Cohort Study. The rs174556 FADS SNP was genotyped in 1516 mothers and 1515 children. Associations and gene-diet interactions were tested with linear regression adjusting for potential confounders, including intake of other PUFAs. Women at the 75th percentile of DHA intake had 0.7-d longer pregnancies (P = 0.016) and 28-g heavier infants (P = 0.039) than did women at the 25th percentile of intake. Associations with arachidonic acid intake were of the same order but in the opposite direction. Mothers who were homozygous for the minor allele had 2-d shorter pregnancies (P = 0.035) and infants who were nearly 140 g lighter (P = 0.006) than did mothers who were major allele homozygotes. Post hoc analyses revealed that they had higher prepregnancy BMI (P = 0.020). Among the women homozygous for the minor allele, those at the 75th percentile of DHA intake had 226-g heavier infants than those at the 25th percentile of intake (P = 0.030), whereas DHA intake was not significantly associated with BW in major allele carriers. These findings suggest that maternal and fetal fatty acid requirements during pregnancy depend on maternal genetic variation in LC-PUFA synthesis.

Circulating cardiac troponin T exhibits a diurnal rhythm

OBJECTIVES

The goal of this study was to test the unverified assumption that chronically elevated cardiac troponin T (cTnT) levels fluctuate randomly around a homeostatic set point.

BACKGROUND

The introduction of high-sensitivity cardiac troponin (cTn) assays has improved sensitivity for acute myocardial infarction (AMI). However, many patients with a single positive cTn test result do not have AMI. Therefore, the diagnosis of AMI relies strongly on serial testing and interpretation of cTn kinetics. Essential in this regard is a profound understanding of the biological variation of cTn.

METHODS

Two studies were conducted to assess biological cTnT variation and to investigate the presence of a diurnal rhythm of cTnT. Study 1 comprised 23 male subjects with type 2 diabetes, with no acute cardiovascular disease. Serial venous blood samples were drawn over an 11-h period (8:30 am to 7:30 pm). In study 2, the presence of a diurnal cTnT rhythm was investigated by hourly sampling of 7 subjects from study 1 over 25 h.

RESULTS

In study 1, we observed a gradual decrease in cTnT concentrations during the day (24 ± 2%). This decrease was present in all participants and was most prominent in subjects with the highest baseline cTnT values (Pearson's R 0.93). Diurnal variation of cTnT, as assessed in study 2, was characterized by peak concentrations during morning hours (8:30 am, 17.1 ± 2.9 ng/l), gradually decreasing values during daytime (8:30 pm, 11.9 ± 1.6 ng/l), and rising concentrations during nighttime (8:30 am the next day, 16.9 ± 2.8 ng/l).

CONCLUSIONS

A diurnal cTnT rhythm substantiates the recommendation that all dynamic changes in cTnT should be interpreted in relation to the clinical presentation. Epidemiological studies and risk-stratification protocols with the use of cTnT may benefit from standardized sampling times. (Exercise and Glycemic Control in Type 2 Diabetes; NCT00945165).

Bayesian design for dichotomous repeated measurements with autocorrelation

In medicine and health sciences, binary outcomes are often measured repeatedly to study their change over time. A problem for such studies is that designs with an optimal efficiency for some parameter values may not be efficient for other values. To handle this problem, we propose Bayesian designs which formally account for the uncertainty in the parameter values for a mixed logistic model which allows quadratic changes over time. Bayesian D-optimal allocations of time points are computed for different priors, costs, covariance structures and values of the autocorrelation. Our results show that the optimal number of time points increases with the subject-to-measurement cost ratio, and that neither the optimal number of time points nor the optimal allocations of time points appear to depend strongly on the prior, the covariance structure or on the size of the autocorrelation. It also appears that for subject-to-measurement cost ratios up to five, four equidistant time points, and for larger cost ratios, five or six equidistant time points are highly efficient. Our results are compared with the actual design of a respiratory infection study in Indonesia and it is shown that, selection of a Bayesian optimal design will increase efficiency, especially for small cost ratios.

Genetic, maternal and placental factors in the association between birth weight and physical fitness: a longitudinal twin study

Background

Adult cardiorespiratory fitness and muscle strength are related to all-cause and cardiovascular mortality. Both are possibly related to birth weight, but it is unclear what the importance is of genetic, maternal and placental factors in these associations.

Design

Peak oxygen uptake and measures of strength, flexibility and balance were obtained yearly during adolescence (10–18 years) in 114 twin pairs in the Leuven Longitudinal Twin Study. Their birth weights had been collected prospectively within the East Flanders Prospective Twin Survey.

Results

We identified linear associations between birth weight and adolescent vertical jump (b = 1.96 cm per kg birth weight, P = 0.02), arm pull (b = 1.85 kg per kg birth weight P = 0.03) and flamingo balance (b = −1.82 attempts to stand one minute per kg birth weight, P = 0.03). Maximum oxygen uptake appeared to have a U-shaped association with birth weight (the smallest and largest children had the lowest uptake, P = 0.01), but this association was no longer significant after adjustment for parental BMI. Using the individual twin’s deviation from his own twin pair’s average birth weight, we found positive associations between birth weight and adolescent vertical jump (b = 3.49, P = 0.0007) and arm pull (b = 3.44, P = 0.02). Δ scores were calculated within the twin pairs as first born twin minus second born twin. Δ birth weight was associated with Δ vertical jump within MZ twin pairs only (b = 2.63, P = 0.009), which indicates importance of placental factors.

Conclusions

We found evidence for an association between adolescent physical performance (strength, balance and possibly peak oxygen uptake) and birth weight. The associations with vertical jump and arm pull were likely based on individual, more specifically placental (in the case of vertical jump) factors. Our results should be viewed as hypothesis-generating and need confirmation, but potentially support preventive strategies to optimize birth weight, for example via placental function, to target later fitness and health.

A comparison of classroom and online asynchronous problem-based learning for students undertaking statistics training as part of a Public Health Masters degree

This case-study compared traditional, face-to-face classroom-based teaching with asynchronous online learning and teaching methods in two sets of students undertaking a problem-based learning module in the multilevel and exploratory factor analysis of longitudinal data as part of a Masters degree in Public Health at Maastricht University. Students were allocated to one of the two study variants on the basis of their enrolment status as full-time or part-time students. Full-time students (n = 11) followed the classroom-based variant and part-time students (n = 12) followed the online asynchronous variant which included video recorded lectures and a series of asynchronous online group or individual SPSS activities with synchronous tutor feedback. A validated student motivation questionnaire was administered to both groups of students at the start of the study and a second questionnaire was administered at the end of the module. This elicited data about student satisfaction with the module content, teaching and learning methods, and tutor feedback. The module coordinator and problem-based learning tutor were also interviewed about their experience of delivering the experimental online variant and asked to evaluate its success in relation to student attainment of the module's learning outcomes. Student examination results were also compared between the two groups. Asynchronous online teaching and learning methods proved to be an acceptable alternative to classroom-based teaching for both students and staff. Educational outcomes were similar for both groups, but importantly, there was no evidence that the asynchronous online delivery of module content disadvantaged part-time students in comparison to their full-time counterparts.

Renal responses to long-term carotid baroreflex activation therapy in patients with drug-resistant hypertension

Carotid baroreflex activation has been demonstrated to provide enduring reductions in arterial blood pressure. The aim of this study was to investigate the effect of long-term therapy on renal function. A total of 322 patients were enrolled in the Rheos Pivotal Trial. Group 1 consisted of 236 patients who started baroreflex activation therapy 1 month after device implantation, whereas in the 86 patients from group 2 the device was activated 6 months later. Serum creatinine and urine albumin/creatinine ratio were collected at screening (before device activation), and at months 6 and 12. Multilevel statistical analyses were adjusted for various covariables. Serum creatinine increased from 78 to 84 μmol/L, and glomerular filtration rate decreased from 92 to 87 mL/min per 1.73 m(2) in group 1 at month 6 (P<0.05). These values did not change any further after 12 months of therapy. Patients with highest glomerular filtration rate showed the greatest decrease in glomerular filtration. Group 2 showed the same trends as group 1 even before device activation at month 6. Systolic blood pressure reduction seemed to be significantly related to the change in glomerular filtration rate in both groups. Albumin/creatinine ratio did not change in both groups during follow-up. In conclusion, baroreflex activation therapy in hypertensive patients is associated with an initial mild decrease in glomerular filtration rate, which may be considered as a normal hemodynamic response to the drop in blood pressure. Long-term treatment does not result in further decrease in renal function, indicating baroreflex activation as a safe and effective therapy.

The prevalence and management of heart failure in Dutch nursing homes; design of a multi-centre cross-sectional study

BACKGROUND

Heart failure is likely to be particularly prevalent in the nursing home population, but reliable data about the prevalence of heart failure in nursing homes are lacking. Therefore the aims of this study are to investigate (a) the prevalence and management of heart failure in nursing home residents and (b) the relation between heart failure and care dependency as well as heart failure and quality of life in nursing home residents.

METHODS/DESIGN

Nursing home residents in the southern part of the Netherlands, aged over 65 years and receiving long-term somatic or psychogeriatric care will be included in the study. A panel of two cardiologists and a geriatrician will diagnose heart failure based on data collected from actual clinical examinations (including history, physical examination, ECG, cardiac markers and echocardiography), patient records and questionnaires. Care dependency will be measured using the Care Dependency Scale. To measure the quality of life of the participating residents, the Qualidem will be used for psychogeriatric residents and the SF-12 and VAS for somatic residents.

CONCLUSION

The study will provide an insight into the actual prevalence and management of heart failure in nursing home residents as well as their quality of life and care dependency.

TRIAL REGISTRATION

Dutch trial register NTR2663.

Influence of multimorbidity on cognition in a normal aging population: a 12-year follow-up in the Maastricht Aging Study

OBJECTIVE

The prevalence of multimorbidity has risen considerably because of the increase in longevity and the rapidly growing number of older individuals. Today, only little is known about the influence of multimorbidity on cognition in a normal healthy aging population. The primary aim of the present study was to investigate the effect of multimorbidity on cognition over a 12-year period in an adult population with a large age range.

METHODS

Data were collected as part of the Maastricht Aging Study (MAAS), a prospective study into the determinants of cognitive aging. Eligible MAAS participants (N = 1763), 24-81 years older, were recruited from the Registration Network Family Practices (RNH) which enabled the use of medical records. The association between 96 chronic diseases, grouped into 23 disease clusters, and cognition on baseline, at 6 and 12 years of follow-up, were analyzed. Cognitive performance was measured in two main domains: verbal memory and psychomotor speed. A multilevel statistical analysis, a method that respects the hierarchical data structure, was used.

RESULTS

Multiple disease clusters were associated with cognition during a 12-year follow-up period in a healthy adult population. The disease combination malignancies and movement disorders multimorbidity also appeared to significantly affect cognition.

CONCLUSIONS

The current results indicate that a variety of medical conditions adversely affects cognition. However, these effects appear to be small in a normal healthy aging population.

Changes in the coping styles of spouses and the influence of these changes on their psychosocial functioning the first year after a patient's stroke

OBJECTIVE

The objective of this study was to examine the changes in spouses' coping styles that occur in the first year after a patient's stroke and the influence of these changes on the spouses' psychosocial functioning.

METHODS

A total of 211 spouses of patients with stroke were assessed at three different time points using self-reported questionnaires (at the time of the patient's admission to inpatient rehabilitation, 2 months after discharge and 1 year poststroke). We used linear mixed-model and multiple linear regression analyses to analyse the data.

RESULTS

Spouses' use of an active coping style decreased significantly in the first year poststroke. There were no significant overall changes in the use of a passive coping style. The use of a passive coping style at admission and increases in passive coping style in the first year poststroke predicted worse psychosocial functioning 1 year poststroke. The models explained between 32% and 50% of the variance in quality of life, depressive symptoms and strain.

CONCLUSION

The present study indicates that spouses' passive coping style is maladaptive poststroke when used in the acute as well as in the chronic phase. Use of an active coping style decreases in the first year poststroke, but these decreases do not predict psychosocial outcomes.

Frequency shifts with age in click-evoked otoacoustic emissions of preterm infants

A previous study [Brienesse et al. (1997). Pediatr. Res. 42, 478-483] demonstrated a positive shift with increasing postmenstrual age (PMA) in the frequencies of synchronized spontaneous otoacoustic emissions (SSOAEs) in preterm infants. We used a mixed model approach to describe a shift with PMA in the spectra of click-evoked otoacoustic emissions (CEOAEs) measured in a group of 22 preterm infants. The rate in shift in CEOAE spectral components was found to be frequency dependent, with a mean estimate of 10 Hz/week for frequencies around 2 kHz and 30 Hz/week for frequencies around 4.25 kHz. This rate decreased with increasing PMA. Because SSOAEs are often part of the CEOAE response, a comparison was made between the shifts in SSOAEs and CEOAEs in a sub-group of 16 preterm infants. The results indicate that the shifts found for both types of OAE are similar, which supports a common mechanism for this change in OAE-characteristic. At present it is not clear to what extent developmental processes in the cochlea and the middle ear can account for these frequency shifts in the spectra of CEOAEs and SSOAEs during the preterm period.

On the A-optimality criterion for finding two-color microarray optimal designs

Several studies on two-color microarray experimental designs consider the A-optimality criterion for the assessment and/or search of appropriate/optimal designs. What seems to be widely ignored, however, is the well-known fact that A-optimal designs depend on the choice of scale or code combination of the X-variables. In this article, it is shown that intrinsically different optimal microarray designs will be obtained depending on the chosen code combination of the qualitative factors. Moreover, a substantial loss in efficiency will result when a design, which is optimal for a specific code combination, is used for another one. This coding problematic is also applicable to the admissibility concept.

ODmixed: a tool to obtain optimal designs for heterogeneous longitudinal studies with dropout

ODMixed is a computer program to obtain optimal designs for linear mixed models of longitudinal studies. These designs account for heterogeneous correlated errors and for data with dropout. Designs are compared by using relative efficiencies, e.g., between a D-optimal design for homogeneous data and another for heterogeneous data or between a D-optimal design for complete data against another that optimizes designs when data is missing at random. Two examples are worked out to illustrate how researchers could use this computer program to profit of optimal design theory at the planning stage of longitudinal studies.

Association between white matter hyperintensities and executive decline in mild cognitive impairment is network dependent

White matter hyperintensities (WMH) in Mild Cognitive Impairment (MCI) have been associated with impaired executive functioning, although contradictory findings have been reported. The aim of this study was to examine whether WMH location influenced the relation between WMH and executive functioning in MCI participants (55-90 years) in the European multicenter memory-clinic-based DESCRIPA study, who underwent MRI scanning at baseline (N = 337). Linear mixed model analysis was performed to test the association between WMH damage in three networks (frontal-parietal, frontal-subcortical and frontal-parietal-subcortical network) and change in executive functioning over a 3-year period. WMH in the frontal-parietal and in the frontal-parietal-subcortical network were associated with decline in executive functioning. However, the frontal-subcortical network was not associated with change in executive functioning. Our results suggest that parietal WMH are a significant contributor to executive decline in MCI and that investigation of WMH in the cerebral networks supporting cognitive functions provide a new way to differentiate stable from cognitive declining MCI individuals.

Interactive computer program for optimal designs of longitudinal cohort studies

Many large scale longitudinal cohort studies have been carried out or are ongoing in different fields of science. Such studies need a careful planning to obtain the desired quality of results with the available resources. In the past, a number of researches have been performed on optimal designs for longitudinal studies. However, there was no computer program yet available to help researchers to plan their longitudinal cohort design in an optimal way. A new interactive computer program for the optimization of designs of longitudinal cohort studies is therefore presented. The computer program helps users to identify the optimal cohort design with an optimal number of repeated measurements per subject and an optimal allocations of time points within a given study period. Further, users can compute the loss in relative efficiencies of any other alternative design compared to the optimal one. The computer program is described and illustrated using a practical example.

Does the workplace-smoking ban eliminate differences in risk for environmental tobacco smoke exposure at work?

OBJECTIVES

A workplace-smoking ban in the Netherlands was introduced on January 1, 2004. Before the ban male and low educated employees were at higher risk for exposure to environmental tobacco smoke (ETS). Effective implementation of the ban should result not only in an overall decline of exposure, but also in the disappearance of systematic differences in exposure between subgroups of employees.

METHODS

Data from a Dutch continuous Internet survey were used. From July 2003 through June 2005, 200 respondents were randomly selected each week. The sample consisted of 11,291 non-smoking, working respondents, aged 16-65 years.

RESULTS

ETS exposure decreased among all employees and among subgroups at higher risk before the ban. However, also after the ban, males and low educated employees were still most likely to be exposed to ETS.

CONCLUSIONS

The workplace-smoking ban was effective in reducing ETS exposure among employees. However, after the ban still 52.2% of non-smoking workers reported to be exposed. We did not find the expected stronger effect among employees who were at higher risk. Both before and after implementation of the ban, males and lower educated employees were about two times more likely to be exposed to ETS.

Optimal designs for one- and two-color microarrays using mixed models: a comparative evaluation of their efficiencies

Comparative studies between the one- and two-color microarrays provide supportive evidence for similarities of results on differential gene expression. So far, no design comparisons between the two platforms have been undertaken. With the objective of comparing optimal designs of one- and two-color microarrays in their statistical efficiencies, techniques of design optimization were applied within a mixed model framework. A- and D-optimal designs for the one- and two-color platforms were sought for a 3 x 3 factorial experiment. The results suggest that the choice of the platform will not affect the "subjects to groups" allocation, being concordant in the two designs. However, under financial constraints, the two-color arrays are expected to have a slight upper hand in terms of efficiency of model parameters estimates, once the price of arrays is more expensive than that of subjects. This statement is especially valid for microarray studies envisaging class comparisons.

D-optimal cohort designs for linear mixed-effects models

The D-optimality criterion is used to construct optimal designs for different numbers of independent cohorts, which constitute a number of repeated measurements per subject over time. A cost function for longitudinal data is proposed, and the optimality criterion is optimized taking into account the cost of the study. First, an optimal number of design points for a given number of cohorts and cost was identified. Then, an optimal number of cohorts is identified by comparing the relative efficiencies (REs). A numerical study shows that for models describing the trend of a continuous outcome over time by polynomials, the most efficient number of repeated measurements is equal to the sum of the total number of cohorts and the degree of the polynomial in the model. REs of a purely longitudinal cohort design with only one cohort, and mixed longitudinal and cross-sectional cohort designs with more cohorts are compared. The results show that a purely longitudinal cohort design with only one cohort of subjects measured at the optimal time points is the most efficient design. The findings in this paper show that one can obtain a highly efficient design for parameter estimation with only a few repeated measurements. The results of this study will reduce the cost of data collection and ease the logistical burdens in cohort studies.

The effect of dropout on the efficiency of D-optimal designs of linear mixed models

Dropout is often encountered in longitudinal data. Optimal designs will usually not remain optimal in the presence of dropout. In this paper, we study D-optimal designs for linear mixed models where dropout is encountered. Moreover, we estimate the efficiency loss in cases where a D-optimal design for complete data is chosen instead of that for data with dropout. Two types of monotonically decreasing response probability functions are investigated to describe dropout. Our results show that the location of D-optimal design points for the dropout case will shift with respect to that for the complete and uncorrelated data case. Owing to this shift, the information collected at the D-optimal design points for the complete data case does not correspond to the smallest variance. We show that the size of the displacement of the time points depends on the linear mixed model and that the efficiency loss is moderate.

Coping style mediates impact of stress on alcohol use: a prospective population-based study

AIMS

This study examines the relationship between stressful life-events and alcohol use in a longitudinal cohort study, and investigates whether gender, coping style and social support modify this relationship.

DESIGN, SETTING AND PARTICIPANTS

Data analysed in this paper come from a sample of 1608 men and 1645 women drawn randomly from the cohort known as the Dutch Lifestyle and Health Study, consisting of 16,210 men and women aged 45-70 years, who were followed-up for 4 years (1996-2000).

MEASUREMENT

Alcohol use (recent and in the more distant past), occurrence of threatening life-events, coping style (action, cognitive and emotion coping), social support (perceived, actual support and social contacts) and other potential confounding factors were assessed with five annual self-administered questionnaires. The data were analysed with a mixed-effects modelling technique, controlling for interactions with time and gender.

FINDINGS AND CONCLUSION

An interaction effect was found between experiencing a negative life-event and emotion coping on alcohol use. A positive relationship was found between the occurrence of negative life-events and alcohol use in subjects scoring high on emotion coping, and a negative one among subjects scoring low on emotion coping. Cognitive coping, action coping, actual support, social contacts and gender did not modify the relationship between life-events and alcohol use. However, having a more cognitive coping style or more social contacts was associated with a lower level of alcohol use, whereas having an action coping style and receiving more actual social support was associated with a higher drinking level. It seems plausible that people scoring high on emotion coping, characterized by a passive, resigned, indulgent and self-accusatory coping style, increase their alcohol use after experiencing a negative life-event.

Improving test ordering in primary care: the added value of a small-group quality improvement strategy compared with classic feedback only

PURPOSE

We wanted to evaluate the added value of small peer-group quality improvement meetings compared with simple feedback as a strategy to improve test-ordering behavior. Numbers of tests ordered by primary care physicians are increasing, and many of these tests seem to be unnecessary according to established, evidence-based guidelines.

METHODS

We enrolled 194 primary care physicians from 27 local primary care practice groups in 5 health care regions (5 diagnostic centers). The study was a cluster randomized trial with randomization at the local physician group level. We evaluated an innovative, multifaceted strategy, combining written comparative feedback, group education on national guidelines, and social influence by peers in quality improvement sessions in small groups. The strategy was aimed at 3 specific clinical topics: cardiovascular issues, upper abdominal complaints, and lower abdominal complaints. The mean number of tests per physician per 6 months at baseline and the physicians' region were used as independent variables, and the mean number of tests per physician per 6 months was the dependent variable.

RESULTS

The new strategy was executed in 13 primary care groups, whereas 14 groups received feedback only. For all 3 clinical topics, the decrease in mean total number of tests ordered by physicians in the intervention arm was far more substantial (on average 51 fewer tests per physician per half-year) than the decrease in mean number of tests ordered by physicians in the feedback arm (P = .005). Five tests considered to be inappropriate for the clinical problem of upper abdominal complaints decreased in the intervention arm, with physicians in the feedback arm ordering 13 more tests per 6 months (P = .002). Interdoctor variation in test ordering decreased more in the intervention arm.

CONCLUSION

Compared with only disseminating comparative feedback reports to primary care physicians, the new strategy of involving peer interaction and social influence improved the physicians' test-ordering behavior. To be effective, feedback needs to be integrated in an interactive, educational environment.