Demographic and clinical characteristics of participants.

p-values are calculated using logistic regression and adjusted for age and gender, with the exception for age, which was calculated using linear regression.
‡ Combined p-value from likelihood ratio-test.
† P-value for trend.
* We merged “very wealthy” and “wealthy” and “very poor” and “poor” because of small numbers at the extremes of the distribution, to create three levels of socio-economic status measure to facilitate data modelling.
Demographic and clinical characteristics of participants.