J Epidemiol 2015;25(7):505 doi:10.2188/jea.JE20150075
Letter to the Editor
Pyogenic Liver Abscess and Risk of Acute Pancreatitis Hsiu-Nien Shen1,2 1
Department of Intensive Care Medicine, Chi Mei Medical Center, Tainan, Taiwan Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan
2
Received March 17, 2015; accepted May 10, 2015; released online July 5, 2015 Copyright © 2015 Hsiu-Nien Shen. This is an open access article distributed under the terms of Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
on risk of acute pancreatitis (Table 3 of the article)1 may differ by time-partitioned period.2
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
ACKNOWLEDGMENT Conflicts of interest: None declared.
REFERENCES 1. Lai SW, Liao KF, Lin CL, Chen PC. Pyogenic liver abscess correlates with increased risk of acute pancreatitis: a populationbased cohort study. J Epidemiol. 2015;25:246–53. 2. Ahmed FE, Vos PW, Holbert D. Modeling survival in colon cancer: a methodological review. Mol Cancer. 2007;6:15.
Address for correspondence. Hsiu-Nien Shen, MD, Department of Intensive Care Medicine, Chi Mei Medical Center, No. 901 Chung-Hwa Rd, Yong-Kang District, Tainan, Taiwan (e-mail: [email protected]).
505
Letter to the Editor
Pyogenic Liver Abscess and Risk of Acute Pancreatitis Hsiu-Nien Shen1,2 1
Department of Intensive Care Medicine, Chi Mei Medical Center, Tainan, Taiwan Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan
2
Received March 17, 2015; accepted May 10, 2015; released online July 5, 2015 Copyright © 2015 Hsiu-Nien Shen. This is an open access article distributed under the terms of Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
on risk of acute pancreatitis (Table 3 of the article)1 may differ by time-partitioned period.2
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
ACKNOWLEDGMENT Conflicts of interest: None declared.
REFERENCES 1. Lai SW, Liao KF, Lin CL, Chen PC. Pyogenic liver abscess correlates with increased risk of acute pancreatitis: a populationbased cohort study. J Epidemiol. 2015;25:246–53. 2. Ahmed FE, Vos PW, Holbert D. Modeling survival in colon cancer: a methodological review. Mol Cancer. 2007;6:15.
Address for correspondence. Hsiu-Nien Shen, MD, Department of Intensive Care Medicine, Chi Mei Medical Center, No. 901 Chung-Hwa Rd, Yong-Kang District, Tainan, Taiwan (e-mail: [email protected]).
505
