Temporal Trends in the Incidence and Disability Adjusted Life Years of Schizophrenia in China Over 30 Years

Abstract

Background: Schizophrenia is an important public health problem in China. This study aims to assess the long-term trends in the incidence and disability-adjusted life years (DALYs) rate of schizophrenia in China between 1990 and 2019.

Methods: The incidence and DALYs data were drawn from the Global Burden of Disease Study 2019, and an age-period-cohort model was used in the analysis.

Results: The age-standardized incidence rate (ASIR) and age-standardized DALYs rate (ASDR) of schizophrenia increased by 0.3 and 3.7% for both sexes between 1990 and 2019. For males, the local drift for incidence was higher than 0 (P < 0.05) in those aged 10 to 29 years (local drifts, 0.01 to 0.26%) and lower than 0 (P < 0.05) in those aged 35 to 74 years (local drifts, -1.01 to -0.06%). For females, the local drift was higher than 0 (P < 0.05) in those aged 10 to 34 years (local drifts, 0.05 to 0.26%) and lower than 0 (P < 0.05) in those aged 40 to 74 years (local drifts, -0.86 to -0.11%). The local drift for DALYs rate was higher than 0 (P < 0.05) in the age group from 10 to 69 years (local drifts, 0.06 to 0.26% for males and 0.06 to 0.28% for females). The estimated period and cohort relative risks (RR) for DALYs rate of schizophrenia were found in monotonic upward patterns, and the cohort RR for the incidence increased as the birth cohort moved forward starting with those born in 1972.

Conclusion: Although the crude incidence of schizophrenia has decreased in China, the ASIR, ASDR, and crude DALYs rate all showed a general increasing trend over the last three decades. The DALYs rate continue to increase as the birth cohort moved forward, and the increasing trend of incidence was also found in individuals born after 1972. More efforts are needed to promote mental health in China.

Keywords: China; age-period-cohort analysis; disability adjusted life years (DALYs); incidence; schizophrenia; trends.

FIGURE 1

Trends in age-standardized incidence rate (ASIR) and crude incidence rate (CIR) of schizophrenia in China by sex, 1990 to 2019: (A) ASIR and CIR for both sexes, (B) ASIR and CIR for males and females. The Global Burden of Disease Study 2019 global age-standard population was used.

FIGURE 2

Trends in crude disability adjusted life years (DALYs) rate and age-standardized DALYs rate (ASDR) of schizophrenia in China by sex, 1990 to 2019: (A) ASDR and crude DALYs rate for both sexes, (B) ASDR and crude DALYs rate for males and females. The Global Burden of Disease Study 2019 global age-standard population was used.

FIGURE 3

Local drift values for the incidence and disability adjusted life years (DALYs) rate of schizophrenia in China. Age group–specific annual percent change (local drift) in the incidence (A) and DALYs rate (B) of schizophrenia and corresponding 95% confidence intervals.

FIGURE 4

Longitudinal age curves of the incidence and disability adjusted life years (DALYs) rate of schizophrenia in China: (A) incidence, (B) DALYs rate. Fitted longitudinal age-specific rates of the incidence/DALYs rate of schizophrenia (per 100,000 person-years) and the corresponding 95% confidence intervals (some of them were too narrow to show in the figure).

FIGURE 5

Period rate ratios (RR) of the incidence and and disability adjusted life years (DALYs) rate of schizophrenia by sex in China: (A) incidence, (B) DALYs rate. The RR of each period compared with the reference period (2000 to 2004) adjusted for age and nonlinear cohort effects and the corresponding 95% confidence intervals. The black dash lines indicates an RR = 1.

FIGURE 6

Cohort rate ratios (RR) of the incidence and disability adjusted life years (DALYs) rate of schizophrenia by sex in China: (A) incidence, (B) DALYs rate. The RR of each cohort compared with the reference cohort (1958 to 1962) adjusted for age and nonlinear period effects and the corresponding 95% confidence intervals. The black dash lines indicates an RR = 1.