Design and Methodological Issues of Within-Person (Split-Body) Randomized Controlled Trials Evaluating a Topical Treatment: A Systematic Review.

BACKGROUND: Topical drugs are often used as first-line treatment for dermatological conditions. A within-person design may then be well adapted: it consists of randomizing lesions/body sites rather than patients, which are then concomitantly treated by the different drugs compared, reducing inter-group variability and therefore requiring fewer patients than the classical parallel-group trial. OBJECTIVES: The aim of this review was to provide a methodological overview of within-person randomized trials (WP-RCTs) in dermatology. METHODS: We searched for eligible trials published between 2017 and 2021 in MEDLINE, Embase, and Central in dermatology journals and the 6 highest-impact-factor general medical journals. Two authors selected publications and extracted data independently. RESULTS: From 1,034 articles identified, we included 54 WP-RCTs, mainly for acne vulgaris, psoriasis, actinic keratosis, and atopic dermatitis. In most of the trials, patients had only 2 lesions/body sites. In none of the trials, did we detect a potential carry-across effect (known to be the major methodological problem in WP-RCTs). Twelve studies reported a care provider applying the treatment, and in 26 studies, the patients themselves applied the treatment. Finally, we also highlight statistical issues for the statistical analysis: overall, 14 (26.9%) studies used a test for independent observations, thus ignoring the between-lesion correlation. CONCLUSION: Our systematic review highlights that despite the publication of the CONSORT checklist extension for WP-RCTs in 2017, this design is rarely used, and when it is, there are methodological and reporting concerns.

Intervention effect estimates in randomised controlled trials conducted in primary care versus secondary or tertiary care settings: a meta-epidemiological study.

BACKGROUND: Many clinical practice guidelines are based on randomised controlled trials conducted in secondary or tertiary care setting and general practitioners frequently question their relevance for primary care patients. Our aim was to compare the intervention effect estimates between primary care setting randomised controlled trials (PC-RCTs) and secondary or tertiary care setting randomised controlled trials (ST-RCTs). METHODS: Meta-epidemiological study of meta-analyses (MAs) of a binary outcome including at least one PC-RCT and one ST-RCT. PC-RCTs were defined as trials recruiting patients in general practices, primary care practices, family practices, community centers or community pharmacies. ST-RCTs were defined as trials recruiting in hospitals, including hospitalized patients, hospital outpatients and patients from emergency departments. For each MA, we estimated a ratio of odds ratio (ROR) by using random-effects meta-regression, with an ROR less than 1 indicating lower estimates of the intervention effect in PC-RCTs than ST-RCTs. Finally, we estimated a combined ROR across MAs by using a random-effects meta-analysis. We performed subgroup analyses considering the type of outcomes (objective vs subjective), type of experimental intervention (pharmacological vs non-pharmacological), and control group (active vs inactive) as well as analyses adjusted on items of the Cochrane Risk of Bias tool. RESULTS: Among 1765 screened reviews, 76 MAs with 230 PC-RCTs and 384 ST-RCTs were selected. The main medical fields were pneumology (13.2%) and psychiatry or addictology (38.2%). Intervention effect estimates did not significantly differ between PC-RCTs and ST-RCTs (ROR = 0.97, 95% confidence interval 0.88 to 1.08), with moderate heterogeneity across MAs (I2 = 45%). Subgroup and adjusted analyses led to consistent results. CONCLUSION: We did not observe any significant difference in intervention effect estimates between PC-RCTs and ST-RCTs. Nevertheless, most of the medical fields in this meta-epidemiological study were not representative of the pathologies encountered in primary care. Further studies with pathologies more frequently encountered in primary care are needed.

Do patients with type 2 diabetes mellitus included in randomised clinical trials differ from general-practice patients? A cross-sectional comparative study.

OBJECTIVES: To compare the characteristics of patients with type 2 diabetes mellitus in general practice and those included in randomised controlled trials on which clinical practice guidelines are based. DESIGN: Cross-sectional comparative study. SETTING: We asked 45 general practitioners from three French Departments to identify the 15 patients with type 2 diabetes mellitus they most recently saw in consultation. In parallel, we selected randomised controlled trials included in the Cochrane systematic review on which the clinical practice guidelines for type 2 diabetes mellitus were based. PARTICIPANTS: We included 675 patients with type 2 diabetes mellitus, and data were collected from 23 randomised controlled trials, corresponding to 36 059 patients. OUTCOME MEASURES: Characteristics of general-practice patients were extracted from medical records by a unique observer. The same baseline characteristics of patients included in randomised controlled trials from the Cochrane systematic review were extracted and meta-analysed. We assessed standardised differences between these two series of baseline characteristics. A difference greater than 0.10 in absolute value was considered meaningful. RESULTS: General-practice patients were older than randomised controlled trial patients (mean (SD) 68.8 (1.1) vs 59.9 years (standardised difference 0.8)) and had a higher body mass index (mean (SD) 31.5 (6.9) vs 28.2 kg/m2 (standardised difference 0.5)) but smoked less (11.0% vs 29.3% (standardised difference -0.6)). They more frequently used antihypertensive drugs (82.1% vs 37.5% (standardised difference 1.2)) but less frequently had a myocardial infarction (7.6% vs 23.1% (standardised difference -1.1)). CONCLUSIONS: Patients with type 2 diabetes mellitus cared for in general practice differ in a number of important aspects from patients included in randomised controlled trials on which clinical practice guidelines are based. This situation hampers the applicability of these guidelines. Future randomised trials should include patients who better fit the 'average' general-practice patient with type 2 diabetes mellitus to help improve the translation of study findings in daily practice.