Pyogenic Liver Abscess and Risk of Acute Pancreatitis

To the Editor: I read with interest the recent article by Lai et al on risk of acute pancreatitis after discharge from hospitalization for pyogenic liver abscess (PLA).1 In this cohort study, the authors found that PLA was associated with an increased risk of acute pancreatitis compared to non-PLA (adjusted hazard ratio 3.00; 95% confidence interval, 2.62–3.43).1 However, the estimate may not be valid because of a violated proportionality assumption, which was acknowledged by the authors.1 To deal with non-proportional hazards, it would be more appropriate to use time partitioning or other methods for time-varying covariates,2 instead of modeling using different follow-up periods (as shown in Table 2 of the article).1 Moreover, the interaction effects of PLA and comorbidity on risk of acute pancreatitis (Table 3 of the article)1 may differ by time-partitioned period.2