ABSTRACT: To evaluate the association of adequate allocation concealment and patient blinding with estimates of treatment benefits in osteoarthritis trials.
We performed a meta-epidemiologic study of 16 meta-analyses with 175 trials that compared therapeutic interventions with placebo or nonintervention control in patients with hip or knee osteoarthritis. We calculated effect sizes from the differences in means of pain intensity between groups at the end of followup divided by the pooled SD and compared effect sizes between trials with and trials without adequate methodology.
Effect sizes tended to be less beneficial in 46 trials with adequate allocation concealment compared with 112 trials with inadequate or unclear concealment of allocation (difference -0.15; 95% confidence interval [95% CI] -0.31, 0.02). Selection bias associated with inadequate or unclear concealment of allocation was most pronounced in meta-analyses with large estimated treatment benefits (P for interaction < 0.001), meta-analyses with high between-trial heterogeneity (P = 0.009), and meta-analyses of complementary medicine (P = 0.019). Effect sizes tended to be less beneficial in 64 trials with adequate blinding of patients compared with 58 trials without (difference -0.15; 95% CI -0.39, 0.09), but differences were less consistent and disappeared after accounting for allocation concealment. Detection bias associated with a lack of adequate patient blinding was most pronounced for nonpharmacologic interventions (P for interaction < 0.001).
Results of osteoarthritis trials may be affected by selection and detection bias. Adequate concealment of allocation and attempts to blind patients will minimize these biases.
Arthritis & Rheumatism 11/2009; 61(12):1633-41. · 7.87 Impact Factor
ABSTRACT: Herbal medicine (phytotherapy) is widely used, but the evidence for its effectiveness is a matter of ongoing debate. We compared the quality and results of trials of Western phytotherapy and conventional medicine.
A random sample of placebo-controlled trials of Western phytotherapy was identified in a comprehensive literature search (19 electronic databases). Conventional medicine trials matched for condition and type of outcome were selected from the Cochrane Central Controlled Trials Register (issue 1, 2003). Data were extracted in duplicate. Trials described as double-blind, with adequate generation of allocation sequence and adequate concealment of allocation were assumed to be of higher methodological quality.
Eighty-nine herbal medicine and 89 matched conventional medicine trials were analyzed. Studies of Western herbalism were smaller, less likely to be published in English, and less likely to be indexed in MEDLINE than their counterparts from conventional medicine. Nineteen (21%) herbal and four (5%) conventional medicine trials were of higher quality. In both groups, smaller trials showed more beneficial treatment effects than larger trials.
Our findings challenge the widely held belief that the quality of the evidence on the effectiveness of herbal medicine is generally inferior to the evidence available for conventional medicine.
Journal of Clinical Epidemiology 09/2007; 60(8):787-94. · 4.27 Impact Factor
ABSTRACT: High intercoder reliability (ICR) is required in qualitative content analysis for assuring quality when more than one coder is involved in data analysis. The literature is short of standardized procedures for ICR procedures in qualitative content analysis.
To illustrate how ICR assessment can be used to improve codings in qualitative content analysis.
Key steps of the procedure are presented, drawing on data from a qualitative study on patients' perspectives on low back pain.
First, a coding scheme was developed using a comprehensive inductive and deductive approach. Second, 10 transcripts were coded independently by two researchers, and ICR was calculated. A resulting kappa value of .67 can be regarded as satisfactory to solid. Moreover, varying agreement rates helped to identify problems in the coding scheme. Low agreement rates, for instance, indicated that respective codes were defined too broadly and would need clarification. In a third step, the results of the analysis were used to improve the coding scheme, leading to consistent and high-quality results.
The quantitative approach of ICR assessment is a viable instrument for quality assurance in qualitative content analysis. Kappa values and close inspection of agreement rates help to estimate and increase quality of codings. This approach facilitates good practice in coding and enhances credibility of analysis, especially when large samples are interviewed, different coders are involved, and quantitative results are presented.
Nursing research 57(2):113-7. · 1.80 Impact Factor