Mathematical pattern of Kessler psychological distress distribution in the general population of the U.S. and Japan

Abstract

Background Although the 6-item Kessler psychological scale (K6) is a useful depression screening scale in clinical settings and epidemiological surveys, little is known about the distribution model of the K6 score in the general population. Using four major national survey datasets from the United States and Japan, we explored the mathematical pattern of the K6 distributions in the general population. Methods We analyzed four datasets from the National Health Interview Survey, the National Survey on Drug Use and Health, and the Behavioral Risk Factor Surveillance System in the United States, and the Comprehensive Survey of Living Conditions in Japan. We compared the goodness of fit between three models: exponential, power law, and quadratic function models. Graphical and regression analyses were employed to investigate the mathematical patterns of the K6 distributions. Results The exponential function had the best fit among the three models. The K6 distributions exhibited an exponential pattern, except for the lower end of the distribution across the four surveys. The rate parameter of the K6 distributions was similar across all surveys. Conclusions Our results suggest that, regardless of different sample populations and methodologies, the K6 scores exhibit a common mathematical distribution in the general population. Our findings will contribute to the development of the distribution model for such a depression screening scale.

The impact of coronavirus disease 2019 (COVID-19) in Japanese companion animal clinics

“…According to the K6 scores, the adjusted prevalence of SMI among workers in veterinary clinics, 11.1%, and that of veterinary nurses, 14.9%, were high compared with the global prevalence of depression before COVID-19, 4.4% [ 38 ]. The prevalence of SMI K6 cutoff 12/13 among Japanese citizens in 2016 was reported to be 3.9% [ 34 ]. The respondents in the present study are only from a working population, while the global and Japanese prevalences of SMI [ 34 , 38 ] included those not working due to SMI; the results suggested that workers in companion animal clinics are distressed at higher levels than in the general population before COVID-19 pandemic.…”

“…The prevalence of SMI K6 cutoff 12/13 among Japanese citizens in 2016 was reported to be 3.9% [ 34 ]. The respondents in the present study are only from a working population, while the global and Japanese prevalences of SMI [ 34 , 38 ] included those not working due to SMI; the results suggested that workers in companion animal clinics are distressed at higher levels than in the general population before COVID-19 pandemic. A high proportion (9%) of 30–39-year-old veterinarians with serious psychological distress was reported in 2015 from the United States of America [ 22 ].…”

“…A high proportion (9%) of 30–39-year-old veterinarians with serious psychological distress was reported in 2015 from the United States of America [ 22 ]. The prevalence of SMI (K6 >=13) among general population in the United States in 2018 by the National Health Interview Survey was 4.0% [ 34 ], and the prevalence among veterinarians may be higher than general population. However, a risk factor in the present study, distress by not going out to avoid infection with SARS-CoV-2, should have been common among general population under the pandemic.…”

Subjective wellbeing and psychological symptoms of university students during the COVID-19 pandemic: Results of a structured telephone interview in a large sample of university students

“…Generally, K6-scores show a right skew ( Tomitaka et al, 2019 ) across different age groups; both in adolescent ( Green et al, 2010 ; Peiper et al, 2014 ) and adult samples ( Kang et al, 2015 ; Tomitaka and Furukawa, 2021 ). The majority of respondents report minimal or minor psychological distress (K6 score up to 4).…”

The Impact of Gender and Age Differences and Infectious Disease Symptoms on Psychological Distress in Quarantined Asymptomatic or Mildly Ill COVID-19 Patients in Japan

“…Each item is rated on a scale of 0 to 4, with the total score ranging from 0 to 24; the higher the score, the greater the psychological distress. It is an excellent screening tool for mood and anxiety disorders [ 22 , 23 ], and the validity of the Japanese version has been confirmed [ 24 ].…”