AUTHOR=Tomitaka Shinichiro , Kawasaki Yohei , Ide Kazuki , Akutagawa Maiko , Ono Yutaka , Furukawa Toshiaki A. 

TITLE=Stability of the Distribution of Patient Health Questionnaire-9 Scores Against Age in the General Population: Data From the National Health and Nutrition Examination Survey

JOURNAL=Frontiers in Psychiatry

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2018.00390

DOI=10.3389/fpsyt.2018.00390

ISSN=1664-0640

ABSTRACT=<p><bold>Background:</bold> Epidemiological studies using the nine-item Patient Health Questionnaire (PHQ-9) have reported inconsistencies regarding the relationship between age and total scores. To determine whether this discrepancy is due to the stability of the distribution of PHQ-9 total scores against age, we investigated whether the total score distribution remains stable during adulthood, and also investigated the mathematical patterns of the total score distribution.</p><p><bold>Methods:</bold> The present study utilized data from 15,847 participants of the 2009–2014 United States National Health and Nutrition Examination Survey, all of whom responded to all PHQ-9 items. The stability of the total score distribution among different age groups was examined using overlap coefficients and graphical analysis.</p><p><bold>Results:</bold> High overlap coefficients were observed between all age groups for the distributions of PHQ-9 total scores, suggesting that the distribution of PHQ-9 total scores remains stable against age. Graphical analysis demonstrated that distributions of PHQ-9 total scores were similar across age groups. In addition, distributions of PHQ-9 total scores exhibited an exponential pattern, except at the lower end of the distribution.</p><p><bold>Conclusions:</bold> Our findings indicate that the stability of the distribution of PHQ-9 total scores throughout adulthood may underlie inconsistencies in the evidence regarding age-related changes in total depression scores.</p>