Table 3.

Estimated parameters explaining age of onset for patients with bipolar I disorder below a threshold of mean monthly kJ/m²/day of 0.75 UVB light for 1 or more months during the year (N = 6972)

			99% Confidence Interval		Coefficient Significance
Parameters	Coefficient estimate (β)	Standard Error	Lower	Upper	Wald Chi-squared	P
Intercept	40.300	1.0867	38.107	42.429	1375.305	< 0.001
Family history of mood disorders	− 1.914	0.2316	− 2.368	− 1.460	68.309	< 0.001
Cohort age groups
DOB after 1979	− 19.768	1.0344	− 21.796	− 17.741	365.219	< 0.001
DOB 1979–1960	− 13.575	1.0509	− 15.635	− 11.516	166.865	< 0.001
DOB 1959–1940	− 7.509	1.0339	− 9.536	− 5.483	52.750	< 0.001
DOB before 1940	0
UVB kJ/m2/day < 0.75 for 1 or more months	− 1.663	0.4853	− 2.614	− 0.712	11.739	< 0.001

Dependent variable: Age of onset (years). Model: intercept, family history of mood disorders (Y/N), cohort age groups, UVB kJ/m²/day < 0.75 for 1 or more months (Y/N). All Sidak pairwise comparisons between family history of mood disorders and cohort age groups were significant at the < 0.001 level