Intracluster correlation coefficients for sample size calculations related to cardiovascular disease prevention and management in primary care practices

The effectiveness of live music in reducing anxiety and depression among patients undergoing haemodialysis. A randomised controlled pilot study

BACKGROUND

Anxiety and depression are highly prevalent disorders among individuals undergoing chronic haemodialysis. For patients with kidney disease, the haemodialysis process often exacerbates these conditions. This study aims to investigate the effects of listening to live classical music on anxiety and depression scales during haemodialysis sessions.

METHODS

A randomised clinical trial was conducted with a group of patients who listened to live classical music during haemodialysis sessions, while the control group received treatment as usual. Anxiety and depression levels were assessed at baseline and after 4 weeks of listening to live music. The study comprised 90 patients.

RESULTS

The results demonstrated a significant decrease in anxiety and depression among the intervention group, who listened to music, compared to the control group, who did not receive this intervention. Specifically, the intervention group, presented a decrease in score on the anxiety scale of -5.35 (p < 0.001) points on average and a decrease in score on the depression scale of -5.88 (p < 0.001) points on average, while in the control group the levels worsened with the progression of time.

CONCLUSION

It is concluded that listening to live classical music during haemodialysis sessions reduces anxiety and depression levels in HD patients. This conclusion adds value to listening to live music in the hospital context, specifically in this case, in haemodialysis rooms.

Statistical Considerations for the Design and Analysis of Pragmatic Trials in Aging Research

Pragmatic trials aim to assess intervention efficacy in usual patient care settings, contrasting with explanatory trials conducted under controlled conditions. In aging research, pragmatic trials are important designs for obtaining real-world evidence in elderly populations, which are often underrepresented in trials. In this review, we discuss statistical considerations from a frequentist approach for the design and analysis of pragmatic trials. When choosing the dependent variable, it is essential to use an outcome that is highly relevant to usual medical care while also providing sufficient statistical power. Besides traditionally used binary outcomes, ordinal outcomes can provide pragmatic answers with gains in statistical power. Cluster randomization requires careful consideration of sample size calculation and analysis methods, especially regarding missing data and outcome variables. Mixed effects models and generalized estimating equations (GEEs) are recommended for analysis to account for center effects, with tools available for sample size estimation. Multi-arm studies pose challenges in sample size calculation, requiring adjustment for design effects and consideration of multiple comparison correction methods. Secondary analyses are common but require caution due to the risk of reduced statistical power and false-discovery rates. Safety data collection methods should balance pragmatism and data quality. Overall, understanding statistical considerations is crucial for designing rigorous pragmatic trials that evaluate interventions in elderly populations under real-world conditions. In conclusion, this review focuses on various statistical topics of interest to those designing a pragmatic clinical trial, with consideration of aspects of relevance in the aging research field.

Improving Sleep Using Mentored Behavioral and Environmental Restructuring (SLUMBER)

OBJECTIVES

To evaluate the impact of a mentoring program to encourage staff-delivered sleep-promoting strategies on sleep, function, depression, and anxiety among skilled nursing facility (SNF) residents.

DESIGN

Modified stepped-wedge unit-level intervention.

SETTING AND PARTICIPANTS

Seventy-two residents (mean age 75 ± 15 years; 61.5% female, 41% non-Hispanic white, 35% Black, 20% Hispanic, 3% Asian) of 2 New York City urban SNFs.

METHODS

Expert mentors provided SNF staff webinars, in-person workshops, and weekly sleep pearls via text messaging. Resident data were collected at baseline, post-intervention (V1), and 3-month follow-up (V2), including wrist actigraphy, resident behavioral observations, Pittsburgh Sleep Quality Index (PSQI), Patient Health Questionnaire-9 (PHQ-9) depression scale, Brief Anxiety and Depression Scale (BADS), Brief Cognitive Assessment Tool (BCAT), and select Minimum Data Set 3.0 (MDS 3.0) measures. Linear mixed models were fit for continuous outcomes and mixed-effects logistic models for binary outcomes. Outcomes were modeled as a function of time. Planned contrasts compared baseline to V1 and V2.

RESULTS

There was significant improvement in PSQI scores from baseline to V1 (P = .009), and from baseline to V2 (P = .008). Other significant changes between baseline and V1 included decreased depression (PHQ-9) (P = .028), increased daytime observed out of bed (P ≤ .001), and increased daytime observed being awake (P < .001). At V2 (vs baseline) being observed out of bed decreased (P < .001). Daytime sleeping by actigraphy increased from baseline to V1 (P = .004), but not V2. MDS 3.0 activities of daily living and pain showed improvements by the second quarter following implementation of SLUMBER (P's ≤ .034). There were no significant changes in BADS or BCAT between baseline and V1 or V2.

CONCLUSIONS AND IMPLICATIONS

SNF residents had improvements in sleep quality and depression with intervention, but improvements were not sustained at 3-month follow-up. The COVID-19 pandemic led to premature study termination, so full impacts remain unknown.

Effectiveness of online training in improving primary care doctors' competency in brief tobacco interventions: A cluster-randomized controlled trial of WHO modules in Delta State, Nigeria

BACKGROUND

The World Health Organization (WHO) strongly recommends that brief tobacco interventions should be routinely offered in primary care. However, medical doctors do not consistently and effectively intervene during their encounters with cigarette smokers. There is a paucity of studies assessing the effect of training on the tobacco intervention competency of primary care doctors in Nigeria.

AIM

To evaluate the effectiveness of online training in improving competency in brief tobacco interventions among primary care doctors in Delta State, Nigeria.

METHODS

A cluster-randomized controlled trial was conducted among eligible doctors working in government-owned facilities. The 22 eligible Local Government Areas (LGAs) served as clusters. The intervention group received a WHO six-hour online course on brief tobacco cessation intervention, delivered via Zoom. The control group received no intervention. A structured questionnaire was sent to participants via WhatsApp before and six months after the training. The primary outcome variables were scores for knowledge, attitude, self-efficacy, and practice. Differences in change of scores between intervention and control groups were assessed with t-test. To adjust for clustering, these inter-group differences were further analyzed using linear mixed-effects regression modeling with study condition modeled as a fixed effect, and LGA of practice entered as a random effect.

RESULTS

The intervention group had a significantly higher mean of change in scores for knowledge (effect size 0.344) and confidence (effect size 0.52).

CONCLUSION

The study shows that training, even online, positively affects clinician competency in brief tobacco intervention. This is important for primary care systems in developing countries. Mandatory in-service training and promotion of the WHO modules are recommended.

Uptake of signposting to web-based resources: pregnant women's use of a preventive web-based intervention

BACKGROUND

Signposting to web-based interventions is becoming increasingly popular in primary care. Most resources are focused on individuals with clinical problems, but less is known about the uptake of general practice (GP) signposted web-based interventions. GPs in Denmark are responsible for scheduled preventive care during pregnancy and the child's first five years. In the "Family Well-being in General Practice" trial the web-based intervention "Resilientchild.dk" is introduced at these consultations. Resilientchild.dk is designed to improve the capacity of parents to understand the mental state of themselves, their partners, and their children. In this study we assess the uptake and use of this web-based intervention.

OBJECTIVE

To describe participant and practice characteristics associated with the use of a web-based psychoeducational intervention. Eligible participants were pregnant women presenting at their first antenatal assessment, usually around 6-10 gestational weeks.

METHODS

The study was nested in a cluster randomised trial of resilientchild.dk. We conducted a relative importance analysis, which allows for determination of the variables most strongly associated with website use. To assess the direction and magnitude of the influences of the identified variables, we applied multinomial generalized linear mixed modelling. A practice random effect allows us to account for clustering of women within practices.

RESULTS

Parity and the absence of a nurse or midwife in the practice were important factors driving a decrease in the likelihood of using resilientchild.dk. Being a student or living outside the capital city were important factors driving an increase in the likelihood of using resilientchild.dk.

CONCLUSION

The data offer unique opportunities to assess the utilisation of a web-based mental health-promotion intervention following advice from a clinician. This study draws conclusions about which patients are likely to access similar resources and which practice characteristics encourage their use.

TRIAL REGISTRATION

Registered in clinicaltrials.gov, Trial number: NCT04129359 Date of registration: 16/10/2019 ( https://clinicaltrials.gov/ct2/show/NCT04129359 ).

Practice facilitation for scale up of clinical decision support for hypertension management: study protocol for a cluster randomized control trial

BACKGROUND

Only half of patients with hypertension have adequately controlled blood pressure. Clinical decision support (CDS) has the potential to overcome barriers to delivering guideline-recommended care and improve hypertension management. However, optimal strategies for scaling CDS have not been well established, particularly in small, independent primary care practices which often lack the resources to effectively change practice routines. Practice facilitation is an implementation strategy that has been shown to support process changes. Our objective is to evaluate whether practice facilitation provided with hypertension-focused CDS can lead to improvements in blood pressure control for patients seen in small primary care practices.

METHODS/DESIGN

We will conduct a cluster randomized control trial to compare the effect of hypertension-focused CDS plus practice facilitation on BP control, as compared to CDS alone. The practice facilitation intervention will include an initial training in the CDS and a review of current guidelines along with follow-up for coaching and integration support. We will randomize 46 small primary care practices in New York City who use the same electronic health record vendor to intervention or control. All patients with hypertension seen at these practices will be included in the evaluation. We will also assess implementation of CDS in all practices and practice facilitation in the intervention group.

DISCUSSION

The results of this study will inform optimal implementation of CDS into small primary care practices, where much of care delivery occurs in the U.S. Additionally, our assessment of barriers and facilitators to implementation will support future scaling of the intervention.

CLINICALTRIALS

gov Identifier: NCT05588466.

Childhood obesity risk increases with increased screen time: a systematic review and dose-response meta-analysis

BACKGROUND

The role of screen time in promoting obesity among children has been reported in previous studies. However, the effects of different screen types and the dose-response association between screen time and obesity among children is not summarized yet. In the current meta-analysis we systematically summarized the association between obesity and screen time of different screen types in a dose-response analysis.

METHODS

A systematic search from Scopus, PubMed and Embase electronic databases was performed. Studies that evaluated the association between screen time and obesity up to September 2021 were retrieved. We included 45 individual studies that were drawn from nine qualified studies into meta-analysis.

RESULTS

The results of the two-class meta-analysis showed that those at the highest category of screen time were 1.2 times more likely to develop obesity [odds ratio (OR) = 1.21; confidence interval (CI) = 1.113, 1.317; I2 = 60.4%; P < 0.001). The results of subgrouping identified that setting, obesity status and age group were possible heterogeneity sources. No evidence of non-linear association between increased screen time and obesity risk among children was observed (P-nonlinearity = 0.310).

CONCLUSION

In the current systematic review and meta-analysis we revealed a positive association between screen time and obesity among children without any evidence of non-linear association. Due to the cross-sectional design of included studies, we suggest further studies with longitudinal or interventional design to better elucidate the observed associations.

Intraclass correlation coefficients for weight loss cluster randomized trials in primary care: The PROPEL trial

The aim of this study was to compute intra-class correlations (ICCs) for weight-related and patient-reported outcomes in a cluster randomized clinical trial (cRCT) for weight loss. Baseline and follow-up data from the Promoting Successful Weight Loss in Primary Care in Louisiana (PROPEL) cRCT were used in this analysis. ICCs were computed for baseline and follow-up measures, and changes in body weight, cardiometabolic risk factors and health-related and weight-related quality of life at 6, 12, 18 and 24 months. Baseline ICCs ranged from 0 for PROMIS measures of anxiety and fatigue to 0.055 for total cholesterol (median = 0.019). The ICCs were higher for changes and decreased over time during follow-up. The ICCs for changes were highest in the pooled sample (intervention and usual care combined) followed by the intervention and usual care groups, respectively. The results demonstrated significant ICCs for several outcomes in a weight loss cRCT. The ICCs differed in magnitude depending on whether baseline versus longitudinal data were used, whether data were combined across treatment arms or were considered separately, and varied across the follow-up period. All these factors must be considered when choosing an ICC to inform sample size estimates for future weight loss cRCTs conducted in primary care settings.

Integration of a multicomponent intervention for hypertension into primary healthcare services in Singapore-A cluster randomized controlled trial

BACKGROUND

Despite availability of clinical practice guidelines for hypertension management, blood pressure (BP) control remains sub-optimal (<30%) even in high-income countries. This study aims to assess the effectiveness of a potentially scalable multicomponent intervention integrated into primary care system compared to usual care on BP control.

METHODS AND FINDINGS

A cluster-randomized controlled trial was conducted in 8 government clinics in Singapore. The trial enrolled 916 patients aged ≥40 years with uncontrolled hypertension (systolic BP (SBP) ≥140 mmHg or diastolic BP (DBP) ≥90 mmHg). Multicomponent intervention consisted of physician training in risk-based treatment of hypertension, subsidized losartan-HCTZ single-pill combination (SPC) medications, nurse training in motivational conversations (MCs), and telephone follow-ups. Usual care (controls) comprised of routine care in the clinics, no MC or telephone follow-ups, and no subsidy on SPCs. The primary outcome was mean SBP at 24 months' post-baseline. Four clinics (447 patients) were randomized to intervention and 4 (469) to usual care. Patient enrolment commenced in January 2017, and follow-up was during December 2018 to September 2020. Analysis used intention-to-treat principles. The primary outcome was SBP at 24 months. BP at baseline, 12 and 24 months was modeled at the patient level in a likelihood-based, linear mixed model repeated measures analysis with treatment group, follow-up, treatment group × follow-up interaction as fixed effects, and random cluster (clinic) effects. A total of 766 (83.6%) patients completed 2-year follow-up. A total of 63 (14.1%) and 87 (18.6%) patients in intervention and in usual care, respectively, were lost to follow-up. At 24 months, the adjusted mean SBP was significantly lower in the intervention group compared to usual care (-3.3 mmHg; 95% CI: -6.34, -0.32; p = 0.03). The intervention led to higher BP control (odds ratio 1.51; 95% CI: 1.10, 2.09; p = 0.01), lower odds of high (>20%) 10-year cardiovascular risk score (OR 0.67; 95% CI: 0.47, 0.97; p = 0.03), and lower mean log albuminuria (-0.22; 95% CI: -0.41, -0.02; p = 0.03). Mean DBP, mortality rates, and serious adverse events including hospitalizations were not different between groups. The main limitation was no masking in the trial.

CONCLUSIONS

A multicomponent intervention consisting of physicians trained in risk-based treatment, subsidized SPC medications, nurse-delivered motivational conversation, and telephone follow-ups improved BP control and lowered cardiovascular risk. Wide-scale implementation of a multicomponent intervention such as the one in our trial is likely to reduce hypertension-related morbidity and mortality globally.

TRIAL REGISTRATION

Trial Registration: Clinicaltrials.gov NCT02972619.

Optimizing blood pressure control by an Information Communication Technology-supported case management (PIA study): study protocol for a cluster-randomized controlled trial of a delegation model for general practices

Background

Longitudinal hypertension control prevents heart attacks, strokes, and other cardiovascular diseases. However, 49% of patients in German family medicine practices do not reach blood pressure (BP) targets (< 140/90 mmHg). Drawing on successful international approaches, the PIA study introduces the PIA information and communication technology system (PIA-ICT) for hypertension management in primary care. The PIA-ICT comprises the PIA-App for patients and the PIA practice management center for practices. Case management includes electronic communication with patients, recall, and stepwise medication adjustments following guidelines. The system supports a physician-supervised delegation model to practice assistants. General practitioners are qualified by eLearning. Patients learn how to obtain reliable BP readings, which they communicate to the practice using the PIA-App.

Methods

The effectiveness of the PIA-Intervention is evaluated in a cluster-randomized study with 60 practices, 120 practice assistants, and 1020 patients. Patients in the intervention group receive the PIA-Intervention; the control group receives usual care. The primary outcome is the BP control rate (BP < 140/90 mmHg) after 12 months. Using a mixed methods approach, secondary outcomes address the acceptance on behalf of physicians, practice assistants, and patients. This includes an evaluation of the delegation model.

Discussion

It is hypothesized that the PIA-Intervention will improve the quality of BP care. Perspectively, it may constitute an important health service model for primary care in Germany.

Trial registration

German Clinical Trials Register DRKS00012680. Registered on May 10, 2019

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05660-4.

Sample sizes for cluster-randomised trials with continuous outcomes: Accounting for uncertainty in a single intra-cluster correlation estimate

Sample size calculations for cluster-randomised trials require inclusion of an inflation factor taking into account the intra-cluster correlation coefficient. Often, estimates of the intra-cluster correlation coefficient are taken from pilot trials, which are known to have uncertainty about their estimation. Given that the value of the intra-cluster correlation coefficient has a considerable influence on the calculated sample size for a main trial, the uncertainty in the estimate can have a large impact on the ultimate sample size and consequently, the power of a main trial. As such, it is important to account for the uncertainty in the estimate of the intra-cluster correlation coefficient. While a commonly adopted approach is to utilise the upper confidence limit in the sample size calculation, this is a largely inefficient method which can result in overpowered main trials. In this paper, we present a method of estimating the sample size for a main cluster-randomised trial with a continuous outcome, using numerical methods to account for the uncertainty in the intra-cluster correlation coefficient estimate. Despite limitations with this initial study, the findings and recommendations in this paper can help to improve sample size estimations for cluster randomised controlled trials by accounting for uncertainty in the estimate of the intra-cluster correlation coefficient. We recommend this approach be applied to all trials where there is uncertainty in the intra-cluster correlation coefficient estimate, in conjunction with additional sources of information to guide the estimation of the intra-cluster correlation coefficient.

Effect of a self-care educational intervention to improve self-care adherence among patients with chronic heart failure: a clustered randomized controlled trial in Northwest Ethiopia

BACKGROUND

As the burden of cardiovascular disease increases in sub-Saharan Africa, there is a growing need for low-cost interventions to mitigate its impact. Providing self-care health education to patients with chronic heart failure (CHF) is recommended as an intervention to prevent complications, improve quality of life, and reduce financial burdens on fragile health systems. However, little is known about health education's effectiveness at improving CHF self-management adherence in sub-Saharan Africa. Therefore the present study aimed to assess the effectiveness of an educational intervention to improve self-care adherence among patients with CHF at Debre Markos and Felege Hiwot Referral Hospitals in Northwest Ethiopia.

METHODS

To address this gap, we adapted a health education intervention based on social cognitive theory comprising of intensive four-day training and, one-day follow-up sessions offered every four months. Patients also received illustrated educational leaflets. We then conducted a clustered randomized control trial of the intervention with 186 randomly-selected patients at Debre Markos and Felege Hiwot referral hospitals. We collected self-reported data on self-care behavior before each educational session. We analyzed these data using a generalized estimating equations model to identify health education's effect on a validated 8-item self-care adherence scale.

RESULTS

Self-care adherence scores were balanced at baseline. After the intervention, patients in the intervention group (n = 88) had higher adherence scores than those in the control group (n = 98). This difference was statistically significant (β = 4.15, p < 0.05) and increased with each round of education. Other factors significantly associated with adherence scores were being single (β = - 0.25, p < 0.05), taking aspirin (β = 0.76, p < 0.05), and having a history of hospitalization (β = 0.91, p < 0.05).

CONCLUSIONS

We find that self-care education significantly improved self-care adherence scores among CHF patients. This suggests that policymakers should consider incorporating self-care education into CHF management.

TRIAL REGISTRATION NUMBER

PACTR201908812642231.

Two Questions About the Design of Cluster Randomized Trials: A Tutorial

This is a short tutorial on two key questions that pertain to cluster randomized trials (CRTs): 1) Should I perform a CRT? and 2) If so, how do I derive the sample size? In summary, a CRT is the best option when you "must" (e.g., the intervention can only be administered to a group) or you "should" (e.g., because of issues such as feasibility and contamination). CRTs are less statistically efficient and usually more logistically complex than individually randomized trials, and so reviewing the rationale for their use is critical. The most straightforward approach to the sample size calculation is to first perform the calculation as if the design were randomized at the level of the patient and then to inflate this sample size by multiplying by the "design effect", which quantifies the degree to which responses within a cluster are similar to one another. Although trials with large numbers of small clusters are more statistically efficient than those with a few large clusters, trials with large clusters can be more feasible. Also, if results are to be compared across individual sites, then sufficient sample size will be required to attain adequate precision within each site. Sample size calculations should include sensitivity analyses, as inputs from the literature can lack precision. Collaborating with a statistician is essential. To illustrate these points, we describe an ongoing CRT testing a mobile-based app to systematically engage families of intensive care unit patients and help intensive care unit clinicians deliver needs-targeted palliative care.

Mobile phone-based interventions for improving adherence to medication prescribed for the primary prevention of cardiovascular disease in adults

BACKGROUND

Cardiovascular disease (CVD) is a major cause of disability and mortality globally. Premature fatal and non-fatal CVD is considered to be largely preventable through the control of risk factors by lifestyle modifications and preventive medication. Lipid-lowering and antihypertensive drug therapies for primary prevention are cost-effective in reducing CVD morbidity and mortality among high-risk people and are recommended by international guidelines. However, adherence to medication prescribed for the prevention of CVD can be poor. Approximately 9% of CVD cases in the EU are attributed to poor adherence to vascular medications. Low-cost, scalable interventions to improve adherence to medications for the primary prevention of CVD have potential to reduce morbidity, mortality and healthcare costs associated with CVD.

OBJECTIVES

To establish the effectiveness of interventions delivered by mobile phone to improve adherence to medication prescribed for the primary prevention of CVD in adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and two other databases on 7 January 2020. We also searched two clinical trials registers on 5 February 2020. We searched reference lists of relevant papers. We applied no language or date restrictions.

SELECTION CRITERIA

We included randomised controlled trials investigating interventions delivered wholly or partly by mobile phones to improve adherence to cardiovascular medications prescribed for the primary prevention of CVD. We only included trials with a minimum of one-year follow-up in order that the outcome measures related to longer-term, sustained medication adherence behaviours and outcomes. Eligible comparators were usual care or control groups receiving no mobile phone-delivered component of the intervention.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. The main outcomes of interest were objective measures of medication adherence (blood pressure (BP) and cholesterol), CVD events, and adverse events. We contacted study authors for further information when this was not reported.

MAIN RESULTS

We included 14 trials with 25,633 randomised participants. Participants were recruited from community-based primary and tertiary care or outpatient clinics. The interventions varied widely from those delivered solely through short messaging service (SMS) to those involving a combination of modes of delivery, such as SMS in addition to healthcare worker training, face-to-face counselling, electronic pillboxes, written materials, and home blood pressure monitors. Some interventions only targeted medication adherence, while others additionally targeted lifestyle changes such as diet and exercise. Due to heterogeneity in the nature and delivery of the interventions and study populations, we reported most results narratively, with the exception of two trials which were similar enough to meaningfully pool in meta-analyses. The body of evidence for the effect of mobile phone-based interventions on objective outcomes of adherence (BP and cholesterol) was of low certainty, due to most trials being at high risk of bias, and inconsistency in outcome effects. Two trials were at low risk of bias. Among five trials (total study enrolment: 5441 participants) recording low-density lipoprotein cholesterol (LDL-C), two studies found evidence for a small beneficial intervention effect on reducing LDL-C (-5.30 mg/dL, 95% confidence interval (CI) -8.30 to -2.30; and -9.20 mg/dL, 95% CI -17.70 to -0.70). The other three studies found results varying from a small reduction (-7.7 mg/dL) to a small increase in LDL-C (0.77 mg/dL). All of which had wide confidence intervals that included no effect. Across 13 studies (25,166 participants) measuring systolic blood pressure, effect estimates ranged from a large reduction (MD -12.45 mmHg, 95% CI -15.02 to -9.88) to a small increase (MD 2.80 mmHg, 95% CI 0.30 to 5.30). We found a similar range of effect estimates for diastolic BP, ranging from -12.23 mmHg (95% CI 14.03 to -10.43) to 1.64 mmHg (95% CI -0.55 to 3.83) (11 trials, 19,716 participants). Four trials showed intervention benefits for systolic and diastolic BP with confidence intervals excluding no effect, and among these were all three of the trials evaluating self-monitoring of blood pressure with mobile phone-based telemedicine. The fourth trial included SMS and provider support (with additional varied features). Seven studies (19,185 participants) reported 'controlled' BP as an outcome, and intervention effect estimates varied from negligible effects (odds ratio (OR) 1.01, 95% CI 0.76 to 1.34) to large improvements in BP control (OR 2.41, 95% CI: 1.57 to 3.68). The three trials of clinician training or decision support combined with SMS (with additional varied features) had confidence intervals encompassing benefits and harms, with point estimates close to zero. Pooled analyses of the two trials of interventions solely delivered through SMS were indicative of little or no beneficial intervention effect on systolic BP (MD -1.55 mmHg, 95% CI -3.36 to 0.25; I2 = 0%) and small increases in controlled BP (OR 1.32, 95% CI 1.06 to 1.65; I2 = 0%). Based on four studies (12,439 participants), there was very low-certainty evidence (downgraded twice for imprecision and once for risk of bias) relating to the intervention effect on combined (fatal and non-fatal) CVD events. Two studies (2535 participants) provided low-certainty evidence for the effect of the intervention on cognitive outcomes, with little or no difference between trial arms for perceived quality of care and satisfaction with treatment. There was moderate-certainty evidence (downgraded due to risk of bias) that the interventions did not cause harm, based on six studies (8285 participants). Three studies reported no adverse events attributable to the intervention. One study reported no difference between groups in experience of adverse effects of statins, and that no participants reported intervention-related adverse events. One study stated that potential side effects were similar between groups. One study reported a similar number of deaths in each arm, but did not provide further information relating to potential adverse events.

AUTHORS' CONCLUSIONS

There is low-certainty evidence on the effects of mobile phone-delivered interventions to increase adherence to medication prescribed for the primary prevention of CVD. Trials of BP self-monitoring with mobile-phone telemedicine support reported modest benefits. One trial at low risk of bias reported modest reductions in LDL cholesterol but no benefits for BP. There is moderate-certainty evidence that these interventions do not result in harm. Further trials of these interventions are warranted.

Sample Size Estimation in Veterinary Epidemiologic Research

In the design of intervention and observational epidemiological studies sample size calculations are used to provide estimates of the minimum number of observations that need to be made to ensure that the stated objectives of a study are met. Justification of the number of subjects enrolled into a study and details of the assumptions and methodologies used to derive sample size estimates are now a mandatory component of grant application processes by funding agencies. Studies with insufficient numbers of study subjects run the risk of failing to identify differences among treatment or exposure groups when differences do, in fact, exist. Selection of a number of study subjects greater than that actually required results in a wastage of time and resources. In contrast to human epidemiological research, individual study subjects in a veterinary setting are almost always aggregated into hierarchical groups and, for this reason, sample size estimates calculated using formulae that assume data independence are not appropriate. This paper provides an overview of the reasons researchers might need to calculate an appropriate sample size in veterinary epidemiology and a summary of sample size calculation methods. Two approaches are presented for dealing with lack of data independence when calculating sample sizes: (1) inflation of crude sample size estimates using a design effect; and (2) simulation-based methods. The advantage of simulation methods is that appropriate sample sizes can be estimated for complex study designs for which formula-based methods are not available. A description of the methodological approach for simulation is described and a worked example provided.

Effect of a nurse-led lifestyle choice and coaching intervention on systolic blood pressure among type 2 diabetic patients with a high atherosclerotic cardiovascular risk: study protocol for a cluster-randomized trial

Background

More than 50% of patients with type 2 diabetes have hypertension in Uganda. Diabetic patients with elevated systolic blood pressure experience higher all-cause mortality and cardiovascular events compared with normotensive diabetic individuals, hence escalating resource utilization and cost of care. The aim of this study is to determine the effect of a nurse-led lifestyle choice and coaching intervention on systolic blood pressure among type 2 diabetic patients with a high atherosclerotic cardiovascular risk.

Methods

This is a cluster-randomized study comprising two arms (intervention and non-intervention—control arm) with four clusters per arm with 388 diabetic patients with a high predicted 10-year atherosclerotic cardiovascular risk. The study will be implemented in 8 health facilities in Uganda. The intervention arm will employ a nurse-led lifestyle choice and coaching intervention. Within the intervention, nurses will be trained to provide structured health education, protocol-based hypertension management, and general atherosclerotic cardiovascular risk factor management, 24-h phone calls, and 2-monthly text messaging. The control group will be constituted by the usual care. The primary outcome measure is the mean difference in systolic blood pressure between the intervention and usual care groups after 6 months. The study is designed to have an 80% statistical power to detect an 8.5-mmHg mean reduction in systolic blood pressure from baseline to 6 months. The unit of analysis for the primary outcome is the individual participants. To monitor the effect of within-cluster correlation, generalized estimating equations will be used to assess the changes over time in systolic blood pressure as a continuous variable.

Discussion

The data generated from this trial will inform change in the policy of shifting task of screening of hypertension and atherosclerotic cardiovascular disease from doctors to nurses.

Trial registration

Pan African Trials Registry PACTR 202001916873358. Registered on 6 October 2019

Statistical analysis plan for management of hypertension and multiple risk factors to enhance cardiovascular health in Singapore: the SingHypertension pragmatic cluster randomized controlled trial

INTRODUCTION

Cardiovascular disease (O'Lone E, Viecelli AK, Craig JC, Tong A, Sautenet B, Herrington WG, et al., Am J Kidney Dis 76(1):109-20, 2020) remains the leading cause of death in Singapore. Uncontrolled hypertension confers the highest attributable risk of CVD and remains a significant public health issue with sub-optimal blood pressure (BP) control rates. The aim of the trial is to evaluate the effectiveness and cost-effectiveness of a multicomponent intervention (MCI) versus usual care on lowering BP among adults with uncontrolled hypertension visiting primary care clinics in Singapore. This article describes the statistical analysis plan for the primary and secondary objectives related to intervention effectiveness.

METHODS

The study is a cluster randomized trial enrolling 1000 participants with uncontrolled hypertension aged ≥ 40 years from eight primary care clinics in Singapore. The unit of randomization is the clinic, with eight clusters (clinics) randomized in a 1:1 ratio to either MCI or usual care. All participants will be assessed at baseline, 12 months, and 24 months with measurements of systolic and diastolic BP, antihypertensive and statin medication use, medication adherence, physical activity level, anthropometric parameters, smoking status, and dietary habits. The primary objective of this study is to assess the effectiveness of MCI versus usual care on mean SBP at the 2-year follow-up. The primary outcome is SBP at 24 months. SBP at baseline, 12, and 24 months will be modeled at the subject level using a likelihood-based, linear mixed-effects model repeated measures (MMRM) analysis with treatment group and follow-up as fixed effects, random cluster (clinic) effects, Gaussian error distribution, and adjustment to degrees of freedom using the Satterthwaite approximation. Secondary outcomes will be analyzed using a similar modeling approach incorporating generalized techniques appropriate for the type of outcome.

DISCUSSION

The trial will allow us to determine whether the MCI has an impact on BP and cardiovascular risk factors over a 2-year follow-up period and inform recommendations for health planners in scaling up these strategies for the benefit of society at large. A pre-specified and pre-published statistical analysis plan mitigates reporting bias and data driven approaches.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02972619 . Registered on 23 November 2016.

Study protocol on Enhanced Primary Healthcare (EnPHC) interventions: a quasi-experimental controlled study on diabetes and hypertension management in primary healthcare clinics

AIM

This paper describes the study protocol, which aims to evaluate the effectiveness of a multifaceted intervention package called 'Enhanced Primary Healthcare' (EnPHC) on the process of care and intermediate clinical outcomes among patients with Type 2 diabetes mellitus (T2DM) and hypertension. Other outcome measures include patients' experience and healthcare providers' job satisfaction.

BACKGROUND

In 2014, almost two-thirds of Malaysia's adult population aged 18 years or older had T2DM, hypertension or hypercholesterolaemia. An analysis of health system performance from 2016 to 2018 revealed that the control and management of diabetes and hypertension in Malaysia was suboptimal with almost half of the patients not diagnosed and just one-quarter of patients with diabetes appropriately treated. EnPHC framework aims to improve diagnosis and effective management of T2DM, hypertension or hypercholesterolaemia and their risk factors by increasing prevention, optimising management and improving surveillance of diagnosed patients.

METHODS

This is a quasi-experimental controlled study which involves 20 intervention and 20 control clinics in two different states in Malaysia, namely Johor and Selangor. The clinics in the two states were matched and randomly allocated to 'intervention' and 'control' arms. The EnPHC framework targets different levels from community to primary healthcare clinics and integrated referral networks.Data are collected via a retrospective chart review (RCR), patient exit survey, healthcare provider survey and an intervention checklist. The data collected are entered into tablet computers which have installed in them an offline survey application. Interrupted time series and difference-in-differences (DiD) analyses will be conducted to report outcomes.

EVALUATION OF RADIATION PROTECTION PRINCIPLES OBSERVANCE IN DENTAL RADIOGRAPHY CENTERS (WEST OF IRAN): CROSS-SECTIONAL STUDY

The aim of this study is to assess the evaluation of radiation protection principles observance in dental radiography centers and hazards. This cross-sectional study was designed to assess level of radiation protection principles in dentistry centers. The present cross-sectional study was conducted by enrolling 103 dentistry centers in Kermanshah province (west of Iran). Our finding illustrates 75.7% of the centers were equipped with an intraoral radiography. Although observance principles of radiation protection for patient at dentistry center were at appropriate level (97.3%), the observance of the protective principles was not adequate for the skilled workers in any center. The most commonly used protective measure was the observance of a distance from patient (97.3%) and the minimum protective measures such as the use of high-speed film (1.4%). According to results in this study, the knowledge and practice of radiation protection are not satisfactory.

Intra-cluster correlation coefficients in primary care patients with type 2 diabetes and hypertension

Introduction

There are few sources of published data on intra-cluster correlation coefficients (ICCs) amongst patients with type 2 diabetes (T2D) and/or hypertension in primary care, particularly in low- and middle-income countries. ICC values are necessary for determining the sample sizes of cluster randomized trials. Hence, we aim to report the ICC values for a range of measures from a cluster-based interventional study conducted in Malaysia.

Method

Baseline data from a large study entitled Evaluation of Enhanced Primary Health Care interventions in public health clinics (EnPHC-EVA: Facility) were used in this analysis. Data from 40 public primary care clinics were collected through retrospective chart reviews and a patient exit survey. We calculated the ICCs for processes of care, clinical outcomes and patient experiences in patients with T2D and/or hypertension using the analysis of variance approach.

Results

Patient experience had the highest ICC values compared to processes of care and clinical outcomes. The ICC values ranged from 0.01 to 0.48 for processes of care. Generally, the ICC values for processes of care for patients with hypertension only are higher than those for T2D patients, with or without hypertension. However, both groups of patients have similar ICCs for antihypertensive medications use. In addition, similar ICC values were observed for clinical outcomes, ranging from 0.01 to 0.09. For patient experience, the ICCs were between 0.03 (proportion of patients who are willing to recommend the clinic to their friends and family) and 0.25 (for Patient Assessment of Chronic Illness Care item 9, Given a copy of my treatment plan).

Conclusion

The reported ICCs and their respective 95% confidence intervals for T2D and hypertension will be useful for estimating sample sizes and improving efficiency of cluster trials conducted in the primary care setting, particularly for low- and middle-income countries.

Reducing cardiovascular risk among people living with HIV: Rationale and design of the INcreasing Statin Prescribing in HIV Behavioral Economics REsearch (INSPIRE) randomized controlled trial

Cardiovascular disease (CVD) is a major cause of morbidity among people living with HIV (PLWH). Statins can safely and effectively reduce CVD risk in PLWH, but evidence-based statin therapy is under-prescribed in PLWH. Developed using an implementation science framework, INcreasing Statin Prescribing in HIV Behavioral Economics REsearch (INSPIRE) is a stepped-wedge cluster randomized trial that addresses organization-, clinician- and patient-level barriers to statin uptake in Los Angeles community health clinics serving racially and ethnically diverse PLWH. After assessing knowledge about statins and barriers to clinician prescribing and patient uptake, we will design, implement and measure the effectiveness of (1) educational interventions targeting leadership, clinicians, and patients, followed by (2) behavioral economics-informed clinician feedback on statin uptake. In addition, we will assess implementation outcomes, including changes in clinician acceptability of statin prescribing for PLWH, clinician acceptability of the education and feedback interventions, and cost of implementation.

Intracluster correlation coefficients in the Greater Mekong Subregion for sample size calculations of cluster randomized malaria trials

BACKGROUND

Sample size calculations for cluster randomized trials are a recognized methodological challenge for malaria research in pre-elimination settings. Positively correlated responses from the participants in the same cluster are a key feature in the estimated sample size required for a cluster randomized trial. The degree of correlation is measured by the intracluster correlation coefficient (ICC) where a higher coefficient suggests a closer correlation hence less heterogeneity within clusters but more heterogeneity between clusters.

METHODS

Data on uPCR-detected Plasmodium falciparum and Plasmodium vivax infections from a recent cluster randomized trial which aimed at interrupting malaria transmission through mass drug administrations were used to calculate the ICCs for prevalence and incidence of Plasmodium infections. The trial was conducted in four countries in the Greater Mekong Subregion, Laos, Myanmar, Vietnam and Cambodia. Exact and simulation approaches were used to estimate ICC values for both the prevalence and the incidence of parasitaemia. In addition, the latent variable approach to estimate ICCs for the prevalence was utilized.

RESULTS

The ICCs for prevalence ranged between 0.001 and 0.082 for all countries. The ICC from the combined 16 villages in the Greater Mekong Subregion were 0.26 and 0.21 for P. falciparum and P. vivax respectively. The ICCs for incidence of parasitaemia ranged between 0.002 and 0.075 for Myanmar, Cambodia and Vietnam. There were very high ICCs for incidence in the range of 0.701 to 0.806 in Laos during follow-up.

CONCLUSION

ICC estimates can help researchers when designing malaria cluster randomized trials. A high variability in ICCs and hence sample size requirements between study sites was observed. Realistic sample size estimates for cluster randomized malaria trials in the Greater Mekong Subregion have to assume high between cluster heterogeneity and ICCs. This work focused on uPCR-detected infections; there remains a need to develop more ICC references for trials designed around prevalence and incidence of clinical outcomes. Adequately powered trials are critical to estimate the benefit of interventions to malaria in a reliable and reproducible fashion.

TRIAL REGISTRATION

ClinicalTrials.govNCT01872702. Registered 7 June 2013. Retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT01872702.

Effect of Novartis Access on availability and price of non-communicable disease medicines in Kenya: a cluster-randomised controlled trial

BACKGROUND

Novartis Access is a Novartis programme that offers a portfolio of non-communicable disease medicines at a wholesale price of US$1 per treatment per month in low-income and middle-income countries. We evaluated the effect of Novartis Access in Kenya, the first country to receive the programme.

METHODS

We did a cluster-randomised controlled trial in eight counties in Kenya. Counties (clusters) were randomly assigned to the intervention or the control group with a covariate-constrained randomisation procedure that maximised balance on a set of demographic and health variables. In intervention counties, public and non-profit health facilities were allowed to purchase Novartis Access medicines from the Mission for Essential Drugs and Supplies (MEDS). Data were collected from all facilities served by MEDS and a sample of households in study counties. Households were eligible if they had at least one adult patient who had been diagnosed and prescribed medicines for one of the non-communicable diseases targeted by the programme: hypertension, heart failure, dyslipidaemia, type 2 diabetes, asthma, or breast cancer. Primary outcomes were availability and price of portfolio medicines at health facilities, irrespective of brand; and availability of medicines at patient households. Impacts were estimated with intention-to-treat analysis. This trial is registered with ClinicalTrials.gov (NCT02773095).

FINDINGS

On March 8, 2016, we randomly assigned eight clusters to intervention (four clusters; 74 health facilities; 342 patients) or control (four clusters; 63 health facilities; 297 patients). 69 intervention and 58 control health facilities, and 306 intervention and 265 control patients were evaluated after a 15 month intervention period (last visit February 28, 2018). Novartis Access significantly increased the availability of amlodipine (adjusted odds ratio [aOR] 2·84, 95% CI 1·10 to 7·37; p=0·031) and metformin (aOR 4·78, 95% CI 1·44 to 15·86; p=0·011) at health facilities, but did not affect the availability of portfolio medicines overall (adjusted β [aβ] 0·05, 95% CI -0·01 to 0·10; p=0·096) or their price (aβ 0·48, 95% CI -1·12 to 0·72; p=0·500). The programme did not affect medicine availability at patient households (aOR 0·83, 95% CI 0·44 to 1·57; p=0·569).

INTERPRETATION

Novartis Access had little effect in its first year in Kenya. Access programmes operate within complex health systems and reducing the wholesale price of medicines might not always or immediately translate to improved patient access. The evidence generated by this study will inform Novartis's efforts to improve their programme going forward. The study also contributes to the public evidence base on strategies for improving access to medicines globally.

FUNDING

Sandoz International (a subsidiary of Novartis International).

Intracluster correlation estimates from a World Health Organisation STEPwise approach to surveillance (STEPS) survey for cardiovascular risk factors in Vellore, Tamil Nadu, India

OBJECTIVES

Most World Health Organisation (WHO) STEPS surveys use cluster sampling to assess the prevalence of risk factors for non-communicable diseases (NCDs) for which design effects need to be estimated using intracluster correlation (ICCs) coefficients, for sample size calculation. Although there are many reports of risk factor surveys reported from developing countries, there are very few reports of ICCs for risk factors for NCDs, which can inform planning the appropriate sample size needed for such surveys. This study reports the ICCs for NCD risk factors, obtained from a WHO STEPS survey conducted in Vellore district, in the state of Tamil Nadu, South India.

STUDY DESIGN

Cross-sectional study.

METHODS

A cross-sectional study was carried out in 48 urban clusters (wards) and nine rural clusters (villages) between 2011 and 2012, using the WHO STEPS methodology for assessing behavioural, anthropometric, physical and biochemical risk factors. The ICC estimates for various risk factors were obtained using loneway and xtmelogit commands using STATA to study clustering of risk factors.

RESULTS

The number of respondents was 6196 adults aged 30-64 years. The median ICC of cardiovascular risk factors in the urban area was 0.046, while it was 0.064 in the rural area. Clustering was higher for behavioural risk factors such as physical activity (ICC: 0.179 rural, 0.049 urban) and fruit and vegetable intake (ICC: 0.105 rural, 0.091 urban) as compared with physical risk factors (ICCs for hypertension: 0.044 rural, 0.006 urban; body mass index: 0.046 rural, 0.041 urban) and biochemical outcomes such as fasting plasma glucose (ICC: 0.017 rural, 0.027 urban).

CONCLUSIONS

This study provides estimates of ICCs for cardiovascular risk factors from Vellore, South India, as such data have not been reported from WHO STEPS surveys in India or neighbouring countries. Such estimates of ICCs if reported from various WHO STEPS being carried out across the country can contribute to better planning of epidemiological surveys. Clustering of behavioural risk factors at village/ward level as seen in this study points to the need for community-based interventions for health promotion, as spatial clustering influences behaviour, which in turn affects chronic disease outcomes.

Imaging use for low back pain by Ontario primary care clinicians: protocol for a mixed methods study - the Back ON study

BACKGROUND

At any one time, one in every five Canadians has low back pain (LBP), and LBP is one of the most common health problems in primary care. Guidelines recommend that imaging not be routinely performed in patients presenting with LBP without signs or symptoms indicating a potential pathological cause. Yet imaging rates remain high for many patients who present without such indications. Inappropriate imaging can lead to inappropriate treatments, results in worse health outcomes and causes harm from unnecessary radiation. There is a need to understand the extent of, and factors contributing to, inappropriate imaging for LBP, and to develop effective strategies that target modifiable barriers and facilitators. The primary study objectives are to determine: 1) The rate of, and factors associated with, inappropriate lumbar spine imaging (x-ray, CT scan and MRI) for people with non-specific LBP presenting to primary care clinicians in Ontario; 2) The barriers and facilitators to reduce inappropriate imaging for LBP in primary care settings.

METHODS

The project will comprise an inception cohort study and a concurrent qualitative study. For the cohort study, we will recruit 175 primary care clinicians (50 each from physiotherapy and chiropractic; 75 from family medicine), and 3750 patients with a new episode of LBP who present to these clinicians. Clinicians will collect data in the clinic, and each participant will be tracked for 12 months using Ontario health administrative and self-reported data to measure diagnostic imaging use and other health outcomes. We will assess characteristics of the clinicians, patients and encounters to identify variables associated with inappropriate imaging. In the qualitative study we will conduct in-depth interviews with primary care clinicians and patients.

DISCUSSION

This will be the first Canadian study to accurately document the extent of the overuse of imaging for LBP, and the first worldwide to include data from the main healthcare professions offering primary care for people with LBP. This study will provide robust information about rates of inappropriate imaging for LBP, along with factors associated with, and an understanding of, potential reasons for inappropriate imaging.

Study protocol for the SMART2D adaptive implementation trial: a cluster randomised trial comparing facility-only care with integrated facility and community care to improve type 2 diabetes outcomes in Uganda, South Africa and Sweden

INTRODUCTION

Type 2 diabetes (T2D) is increasingly contributing to the global burden of disease. Health systems in most parts of the world are struggling to diagnose and manage T2D, especially in low-income and middle-income countries, and among disadvantaged populations in high-income countries. The aim of this study is to determine the added benefit of community interventions onto health facility interventions, towards glycaemic control among persons with diabetes, and towards reduction in plasma glucose among persons with prediabetes.

METHODS AND ANALYSIS

An adaptive implementation cluster randomised trial is being implemented in two rural districts in Uganda with three clusters per study arm, in an urban township in South Africa with one cluster per study arm, and in socially disadvantaged suburbs in Stockholm, Sweden with one cluster per study arm. Clusters are communities within the catchment areas of participating primary healthcare facilities. There are two study arms comprising a facility plus community interventions arm and a facility-only interventions arm. Uganda has a third arm comprising usual care. Intervention strategies focus on organisation of care, linkage between health facility and the community, and strengthening patient role in self-management, community mobilisation and a supportive environment. Among T2D participants, the primary outcome is controlled plasma glucose; whereas among prediabetes participants the primary outcome is reduction in plasma glucose.

ETHICS AND DISSEMINATION

The study has received approval in Uganda from the Higher Degrees, Research and Ethics Committee of Makerere University School of Public Health and from the Uganda National Council for Science and Technology; in South Africa from the Biomedical Science Research Ethics Committee of the University of the Western Cape; and in Sweden from the Regional Ethical Board in Stockholm. Findings will be disseminated through peer-reviewed publications and scientific meetings.

TRIAL REGISTRATION NUMBER

ISRCTN11913581; Pre-results.

Improving Care for Patients With or at Risk for Chronic Kidney Disease Using Electronic Medical Record Interventions: A Pragmatic Cluster-Randomized Trial Protocol

BACKGROUND

Many patients with or at risk for chronic kidney disease (CKD) in the primary care setting are not receiving recommended care.

OBJECTIVE

The objective of this study is to determine whether a multifaceted, low-cost intervention compared with usual care improves the care of patients with or at risk for CKD in the primary care setting.

DESIGN

A pragmatic cluster-randomized trial, with an embedded qualitative process evaluation, will be conducted.

SETTING

The study population comes from the Electronic Medical Record Administrative data Linked Database®, which includes clinical data for more than 140 000 rostered adults cared for by 194 family physicians in 34 clinics across Ontario, Canada. The 34 primary care clinics will be randomized to the intervention or control group.

INTERVENTION

The intervention group will receive resources from the "CKD toolkit" to help improve care including practice audit and feedback, printed educational materials for physicians and patients, electronic decision support and reminders, and implementation support.

MEASUREMENTS

Patients with or at risk for CKD within participating clinics will be identified using laboratory data in the electronic medical records. Outcomes will be assessed after dissemination of the CKD tools and after 2 rounds of feedback on performance on quality indicators have been sent to the physicians using information from the electronic medical records. The primary outcome is the proportion of patients aged 50 to 80 years with nondialysis-dependent CKD who are on a statin. Secondary outcomes include process of care measures such as screening tests, CKD recognition, monitoring tests, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker prescriptions, blood pressure targets met, and nephrologist referral. Hierarchical analytic modeling will be performed to account for clustering. Semistructured interviews will be conducted with a random purposeful sample of physicians in the intervention group to understand why the intervention achieved the observed effects.

CONCLUSIONS

If our intervention improves care, then the CKD toolkit can be adapted and scaled for use in other primary care clinics which use electronic medical records.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02274298.

Geographic Clustering of Cardiometabolic Risk Factors in Metropolitan Centres in France and Australia

Understanding how health outcomes are spatially distributed represents a first step in investigating the scale and nature of environmental influences on health and has important implications for statistical power and analytic efficiency. Using Australian and French cohort data, this study aimed to describe and compare the extent of geographic variation, and the implications for analytic efficiency, across geographic units, countries and a range of cardiometabolic parameters (Body Mass Index (BMI) waist circumference, blood pressure, resting heart rate, triglycerides, cholesterol, glucose, HbA_1c). Geographic clustering was assessed using Intra-Class Correlation (ICC) coefficients in biomedical cohorts from Adelaide (Australia, n = 3893) and Paris (France, n = 6430) for eight geographic administrative units. The median ICC was 0.01 suggesting 1% of risk factor variance attributable to variation between geographic units. Clustering differed by cardiometabolic parameters, administrative units and countries and was greatest for BMI and resting heart rate in the French sample, HbA_1c in the Australian sample, and for smaller geographic units. Analytic inefficiency due to clustering was greatest for geographic units in which participants were nested in fewer, larger geographic units. Differences observed in geographic clustering across risk factors have implications for choice of geographic unit in sampling and analysis, and highlight potential cross-country differences in the distribution, or role, of environmental features related to cardiometabolic health.

Neighborhood clustering of non-communicable diseases: results from a community-based study in Northern Tanzania

Background

In order to begin to address the burden of non-communicable diseases (NCDs) in sub-Saharan Africa, high quality community-based epidemiological studies from the region are urgently needed. Cluster-designed sampling methods may be most efficient, but designing such studies requires assumptions about the clustering of the outcomes of interest. Currently, few studies from Sub-Saharan Africa have been published that describe the clustering of NCDs. Therefore, we report the neighborhood clustering of several NCDs from a community-based study in Northern Tanzania.

Methods

We conducted a cluster-designed cross-sectional household survey between January and June 2014. We used a three-stage cluster probability sampling method to select thirty-seven sampling areas from twenty-nine neighborhood clusters, stratified by urban and rural. Households were then randomly selected from each of the sampling areas, and eligible participants were tested for chronic kidney disease (CKD), glucose impairment including diabetes, hypertension, and obesity as part of the CKD-AFRiKA study. We used linear mixed models to explore clustering across each of the samplings units, and we estimated absolute-agreement intra-cluster correlation (ICC) coefficients (ρ) for the neighborhood clusters.

Results

We enrolled 481 participants from 346 urban and rural households. Neighborhood cluster sizes ranged from 6 to 49 participants (median: 13.0; 25th–75th percentiles: 9–21). Clustering varied across neighborhoods and differed by urban or rural setting. Among NCDs, hypertension (ρ = 0.075) exhibited the strongest clustering within neighborhoods followed by CKD (ρ = 0.440), obesity (ρ = 0.040), and glucose impairment (ρ = 0.039).

Conclusion

The neighborhood clustering was substantial enough to contribute to a design effect for NCD outcomes including hypertension, CKD, obesity, and glucose impairment, and it may also highlight NCD risk factors that vary by setting. These results may help inform the design of future community-based studies or randomized controlled trials examining NCDs in the region particularly those that use cluster-sampling methods.