Statistics
asthma, COPD
RESPIRATORY DISEASE, DISEASE, COPD, ASTHMA, REGRESSION
We analyzed the results first as separate effects for the diagnoses and occupational exposure and then combined them into a single variable and analyzed that in separate models. The separate models used no diagnose and no exposure as reference groups. The combined models used participants without self-reported asthma or COPD diagnosis and without exposure as the reference group. Cox proportional hazards models with follow-up of 24 years were used to compute hazards ratios (HRs) for the diagnoses and exposures. The full adjustment of the models included age, educational level, sex, and smoking status, excluding those without this information.The respiratory disease–related models were computed with a competing-risks regression model, which is based on the Fine-Gray proportional sub-hazards model.The Kaplan-Meier models included participants aged 50 years and older at the baseline of 1996. The survival analysis was done separately for each disease similarly to the regression models. The pairwise comparison used for testing the mean survival times was log-rank (Mantel-Cox) test, and each group was tested against the no diagnosis participants without occupational exposure. The age limit of 50 years was chosen to make the various groups more similar with regards to age.All analyses were carried out using IBM SPSS Statistics Version 27 (IBM Corp, New York, NY) and StataCorp 2021, Stata Statistical Software: Release 17 (StataCorp LLC, College Station, TX). The statistical significance was set at 0.05.