Statistical methods
ABI, PAD
REGRESSION, PAD, EVENTS, EVENT
Patients’ characteristics at baseline are also presented for subgroups defined by the quartiles of PM10 exposure in the study population.To investigate the relationship between the different exposure factors and mortality or incidence of PAD, survival times were modeled by Cox proportional hazards regression, briefly referred to as Cox regression. If multiple target events occurred in a patient during the analysis of the combined endpoint, only the event that occurred first was considered.Missing values rarely appeared (below 2%), on continuous variables such as CRP, eGFR, vitamin D, and ABI they were randomly supplemented with data from the sample. For categorical variables, missing values were assigned to the unexposed group.Effects were presented in the form of HR with associated 95% confidence intervals (CI). The effects of PM10 and NOThe significance level was set to 0.05. For interactions, the estimated HR and 95% CI on each level of the potentially modifying factor were provided. Corrections for multiple testing of hypotheses were not applied.