Reporting results in U.S. clinical trials for obstructive sleep apnea and insomnia: How transparent are they?

Clinical trial transparency is important for scientific research and for the good of the general public. Diversity of study samples by race/ethnicity, gender, and age is important to ensure that results are generalizable. Moreover, reporting results might also be necessary to engage racial/ethnic minorities in clinical research. The primary objective of this study was to describe the results of clinical studies conducted for obstructive sleep apnea (OSA) and insomnia, two of the most prevalent sleep disorders. The secondary objective was to identify which factors were associated with voluntarily reporting the results.

We reviewed ClinicalTrials.gov, the public database of biomedical and behavioral research operated by the United States (U.S.) National Library of Medicine at the National Institutes of Health to ascertain the reports of demographic variables, including race/ethnicity of the studies conducted for OSA and insomnia. Since reporting race/ethnicity was an optional data feature, we searched for publications in PubMed using the unique national clinical trial identification number (NCTID). The national clinical trial identification number is assigned as soon as the trial is registered. The article extraction was conducted by graduate students and supervised by N.J.W.

We identified 427 studies on OSA and 404 studies on insomnia. Results were reported for 122 studies. Based on the 122 studies with results that included studies that were terminated (n = 16) and/or completed (n = 105), and one study was listed as "active" but not recruiting. 46.7% studies involved drugs, 30.3% studied a medical device, and 8.2% investigated behavioral interventions. The age range of subjects was 2-99 years of age and 16.4% included an age range of 35-50 years. Twenty-nine studies (23.8%) reported race/ethnicity in ClinicalTrials.gov. Of these, 74% of subjects were white (n = 2,953); 20% black (n = 822); 1% Asian American (n = 40); 2% Hispanic/Latino (n = 77); and 3% of study subjects identified race/ethnicity as "other" (n = 118). With the PubMed search, we found an additional 24 studies that reported race/ethnicity. There was no difference in reports of race/ethnicity between studies for insomnia and studies for OSA. The intervention type labeled as "behavioral" was a significant predictor (odds ratio: 12.49, P-value ≤ .05, confidence interval: 1.002-155.62) for reporting results.

The National Institutes of Health has mandated federally funded research include women and minorities and that they are representative of the U.S.

Though gender was reported, few investigators and study sponsors reported the results of race/ethnicity, which begs the question about trial transparency for the future of sleep research. Presumably, the lack of reporting is related to low enrollment of ethnic/minorities included in these studies. Nonetheless, our key finding warrants increased attention to minority participation in sleep clinical studies and trial transparency.