Model 1 | Model 2 | Model 3 | Model 4 | Model 5 | |
---|---|---|---|---|---|
Variable | IRR (95%CI) | IRR (95%CI) | IRR (95%CI) | IRR (95%CI) | IRR (95%CI) |
Malea | 0.937 (0.919–0.954) | 0.962 (0.945–0.979) | |||
Age in Yearsa | 1.014 (1.013–1.014) | 1.010 (1.009–1.010) | |||
#Chronic Conditionsa | 1.323 (1.311–1.335) | 1.049 (1.038–1.061) | |||
#Visitsa | 1.029 (1.028–1.030) | 1.022 (1.022–1.023) | |||
#Months of Exposurea | 1.030 (1.023–1.030) | 1.024 (1.023–1.024) | 1.022 (1.022–1.023) | 1.012 (1.011–1.013) | 1.012 (1.011–1.013) |
Intercept | 0.234 (0.226–0.242) | 0.240 (0.232–0.248) | 0.227 (0.219–0.235) | 0.199 (0.193–0.205) | 0.238 (0.231–0.246) |
/ln alphaa | −0.724 (−0.759–0.689) | −0.918 (−0.957–0.879) | −0.900 (−0.938–0.861) | −0.800 (−0.835–0.765) | −1.179 (−1.233–1.134) |
Intercept for Practice-Level Variance | 0.076 (0.074–0.079) | 0.162 (0.157–0.167) | 0.068 (0.066–0.070) | 0.813 (0.789–0.837) | 0.114 (0.111–0.118) |
Note. IRR = incidence rate ratio; CI = confidence interval.
/ln alpha is an added parameter to model over-dispersion of the outcome variable, and its significance indicates the need for negative binomial modelling.
Intercept for practice-level variance is a variance parameter for nesting of patients within practices.
↵a P < 0.001 for this parameter across all models.