Table 2.
Heterogeneity in Schizophrenia Risk Across Data Zones Adjusting for Individual-Level Risk Factors for Schizophrenia
| General contextual effect in schizophrenia risk across data zones, two competing measuresa | ||
|---|---|---|
| Adjustment scenario | Between data zone standard deviation; Random intercept (Standard error of Random Intercept) | Median Incidence Rate Ratio (95% Probability Interval)b |
| None | 0.36 (0.02) | 1.41 (1.34–1.47) |
| Basic individual-level adjustment, i.e., age and its interaction with sex | 0.36 (0.02) | 1.41 (1.35–1.48) |
| Basic individual-level adjustment, childhood residential transience, parental Charlson, parental death and parental imprisonment | 0.33 (0.02) | 1.38 (1.31–1.44) |
| Basic individual-level adjustment, parental age and parental history of mental illness | 0.31 (0.03) | 1.34 (1.27–1.41) |
| Basic individual-level adjustment, parental income, parental education and parental employment status | 0.34 (0.02) | 1.38 (1.31–1.45) |
| Comprehensive individual-level adjustment, all factors above | 0.29 (0.02) | 1.32 (1.26–1.39) |
| Full individual-level adjustment and neighborhood-level age structure | 0.27 (0.02) | 1.30 (1.24–1.36) |
a Estimates were based on multilevel survival analyses, neighborhoods are 1885 novel data zones nested in Denmark’s 98 municipalities. The 579 039 people born in Denmark 1972–1981 were followed for development of schizophrenia. During the follow-up period from 1982 to 2016, a total of 5103 developed schizophrenia during the 17 191 889 person-years at risk
b The Median Incidence Rate Ratio (MRR) quantified the variation between data zones (clusters) by comparing two identical individuals from two randomly chosen data zones. Consider two people with the same covariates chosen randomly from different data zones, the Median Incidence Rate Ratio is the median incidence rate ratio between the person of higher incidence rate and the person of lower incidence rate.