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