Zhen Wang1, Fares Alahdab2, Jehad Almasri2, Qusay Haydour2, Khaled Mohammed2, Abd Moain Abu Dabrh2, Larry J Prokop3, Wedad Alfarkh4, Sumaya Lakis5, Victor M Montori6, Mohammad Hassan Murad2. 1. Robert D and Patricia E Kern Center for the Science of Health Care Delivery, Mayo Clinic, 200 1st Street SW, Rochester, MN 55902, USA; Division of Health Care Policy and Research, Department of Health Sciences Research, Mayo Clinic, 200 1st Street SW, Rochester, MN 55902, USA. Electronic address: Wang.Zhen@mayo.edu. 2. Robert D and Patricia E Kern Center for the Science of Health Care Delivery, Mayo Clinic, 200 1st Street SW, Rochester, MN 55902, USA; Division of Preventive Medicine, Department of Medicine, Mayo Clinic, 200 1st Street SW, Rochester, MN 55902, USA. 3. Mayo Clinic Library, Mayo Clinic, 200 1st Street SW, Rochester, MN 55902, USA. 4. Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 1st Street SW, Rochester, MN 55902, USA. 5. Knowledge and Evaluation Research Unit, Mayo Clinic, 200 1st Street SW, Rochester, MN 55902, USA. 6. Knowledge and Evaluation Research Unit, Mayo Clinic, 200 1st Street SW, Rochester, MN 55902, USA; Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Department of Medicine, Mayo Clinic, 200 1st Street SW, Rochester, MN 55902, USA.
Abstract
OBJECTIVES: To evaluate the presence of extreme findings and fluctuation in effect size in endocrinology. STUDY DESIGN AND SETTINGS: We systematically identified all meta-analyses published in 2014 in the field of endocrinology. Within each meta-analysis, the effect size of the primary binary outcome was compared across studies according to their order of publication. We pooled studies using the DerSimonian and Laird random-effects method. Heterogeneity was evaluated using the I(2) and tau(2). RESULTS: Twelve percent of the included 100 meta-analyses reported the largest effect size in the very first published study. The largest effect size occurred in the first 2 earliest studies in 31% of meta-analyses. When the effect size was the largest in the first published study, it was three times larger than the final pooled effect (ratio of rates, 3.26; 95% confidence interval: 1.80, 5.90). The largest heterogeneity measured by I(2) was observed in 18% of the included meta-analyses when combining the first 2 studies or 17% when combing the first 3 studies. CONCLUSIONS: In endocrinology, early studies reported extreme findings with large variability. This behavior of the evidence needs to be taken into account when used to formulate clinical policies.
OBJECTIVES: To evaluate the presence of extreme findings and fluctuation in effect size in endocrinology. STUDY DESIGN AND SETTINGS: We systematically identified all meta-analyses published in 2014 in the field of endocrinology. Within each meta-analysis, the effect size of the primary binary outcome was compared across studies according to their order of publication. We pooled studies using the DerSimonian and Laird random-effects method. Heterogeneity was evaluated using the I(2) and tau(2). RESULTS: Twelve percent of the included 100 meta-analyses reported the largest effect size in the very first published study. The largest effect size occurred in the first 2 earliest studies in 31% of meta-analyses. When the effect size was the largest in the first published study, it was three times larger than the final pooled effect (ratio of rates, 3.26; 95% confidence interval: 1.80, 5.90). The largest heterogeneity measured by I(2) was observed in 18% of the included meta-analyses when combining the first 2 studies or 17% when combing the first 3 studies. CONCLUSIONS: In endocrinology, early studies reported extreme findings with large variability. This behavior of the evidence needs to be taken into account when used to formulate clinical policies.