Figure 3. Hazard Ratios (HRs) of Schizophrenia Risk by Cumulative Parental Income Scale During Childhood.

The parental income scale represents relative parental income levels and their duration between birth and 15th birthday. The minimum possible score of 4 represents parental income being in the lowest level, quintile 1, across all 4 age points (ie, at birth, and at ages 5, 10, and 15 years). A maximum score of 20, the reference category for HR estimation (HR = 1), represents parental income being consistently in the highest level, quintile 5. A, In the basic adjustment, HRs are adjusted for sex, birth year, and calendar time. B, In the additional adjustment, HRs are adjusted for sex, birth year, calendar time, parental mental disorders, parental educational attainment level, degree of urbanicity at birth, and number of changes in child-parental separation status. Error bars indicate 95% CIs.