Moderate concordance was found between case-only and parallel group designs in systematic comparison

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• 作者：Koen Bernardus Pouwels^a ; ^{k.b.pouwels@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Bianca Mulder^a ; Eelko Hak^a ; ^b
• 关键词：Case crossover ; Self-controlled case series ; Research design ; Crossover studies ; Cohort studies ; Case&ndash ; control studies
• 刊名：Journal of Clinical Epidemiology
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：71
• 期：Complete
• 页码：18-24
• 全文大小：327 K

文摘

To empirically evaluate the concordance of effect estimates between case-only and parallel group designs and to identify predictors of discrepancies.

Study Design and Setting

MEDLINE and EMBASE databases were searched through June 31, 2013. Studies that used both a case-only (case crossover or self-controlled case series) and a parallel group design (cohort or case–control) were identified. Spearman correlation coefficient was used to evaluate the concordance between designs. Z-scores were used to assess whether differences in the effect estimates were common, using an absolute threshold value of 1.96. A prediction model was built to identify predictors of discrepancies.

Results

The search identified 1,367 articles of which 53 were included for analysis. In total, 519 comparisons were made. The correlation coefficient between case-only vs. parallel group studies was 0.64 (P < .001). In 221 of the 519 comparisons (43%), the difference between both study designs was larger than the predetermined threshold. The following predictors of discrepancy were found: intermittent exposure, rare event, acute outcome, length of hazard period, type of case-only design, and sample size (C statistic of 0.783).

Conclusion

The concordance between effect estimates of case-only and parallel group designs is moderate. Such discrepancies could be predicted by failure to meet assumptions of case-only designs.