Trial reportBMC medical research methodology2017
Selection bias and subject refusal in a cluster-randomized controlled trial.
Trial report in BMC medical research methodology, 2017. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT01983813 (Improved Cardiovascular Risk Reduction to Enhance Rural Primary Care), which is not on this map. Cited by 10 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Improved Cardiovascular Risk Reduction to Enhance Rural Primary Care
Who cites it
10 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Pharmacist services for non-hospitalised patients.The Cochrane database of systematic reviews · 2018Pooled it
- Effectiveness of a Yoga-Based Lifestyle Protocol (YLP) in Preventing Diabetes in a High-Risk Indian Cohort: A Multicenter Cluster-Randomized Controlled Trial (NMB-Trial).Frontiers in endocrinology · 2021Trial
- Sustainability of Blood Pressure Reduction in Black Barbershops.Circulation · 2019Trial
- Cluster-Randomized Trial to Evaluate a Centralized Clinical Pharmacy Service in Private Family Medicine Offices.Circulation. Cardiovascular quality and outcomes · 2018Trial
- Considerations for Issues of Regression to the Mean and Contextual Effects in Clinical Trials for Pain in Rheumatic Diseases.Arthritis care & research · 2026Review
- Assessing the representativeness of cluster randomized trials: Evidence from two large pragmatic trials in United States nursing homes.Clinical trials (London, England) · 2023Article
- Article
- Cluster randomized trials of individual-level interventions were at high risk of bias.Journal of clinical epidemiology · 2021Review
- A cluster randomized trial to evaluate a centralized remote clinical pharmacy service in large, health system primary care clinics.Journal of the American College of Clinical Pharmacy : JACCP · 2021Article
- A research tool for measuring non-participation of older people in research on digital health.BMC public health · 2019Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
6 authors.
Funding
Abstract
backgroundSelection bias and non-participation bias are major methodological concerns which impact external validity. Cluster-randomized controlled trials are especially prone to selection bias as it is impractical to blind clusters to their allocation into intervention or control. This study assessed the impact of selection bias in a large cluster-randomized controlled trial.
methodsThe Improved Cardiovascular Risk Reduction to Enhance Rural Primary Care (ICARE) study examined the impact of a remote pharmacist-led intervention in twelve medical offices. To assess eligibility, a standardized form containing patient demographics and medical information was completed for each screened patient. Eligible patients were approached by the study coordinator for recruitment. Both the study coordinator and the patient were aware of the site's allocation prior to consent. Patients who consented or declined to participate were compared across control and intervention arms for differing characteristics. Statistical significance was determined using a two-tailed, equal variance t-test and a chi-square test with adjusted Bonferroni p-values. Results were adjusted for random cluster variation.
resultsThere were 2749 completed screening forms returned to research staff with 461 subjects who had either consented or declined participation. Patients with poorly controlled diabetes were found to be significantly more likely to decline participation in intervention sites compared to those in control sites. A higher mean diastolic blood pressure was seen in patients with uncontrolled hypertension who declined in the control sites compared to those who declined in the intervention sites. However, these findings were no longer significant after adjustment for random variation among the sites. After this adjustment, females were now found to be significantly more likely to consent than males (odds ratio = 1.41; 95% confidence interval = 1.03, 1.92).
conclusionsThough there appeared to be a higher consent rate for females than for males, the overall impact of potential selection bias and refusal to participate was minimal. Without rigorous methodology, selection bias may be a threat to external validity in cluster-randomized trials.
trial registrationNCT01983813 . Date of registration: Oct. 28, 2013.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.