Table 3. Incidence and Adjusted Hazard Ratio of Inflammatory Bowel Disease Based on Follow-Up Period for Patients With Appendectomy Compared With Controls
Appendectomy Appendectomy Appendectomy Appendectomy Appendectomy Appendectomy  Compared to Control  Compared to Control
Yes Yes Yes No No No
Variables
Events
PY
Rate#
Events
PY
Rate#
Crude HR (95% CI) Adjusted HR (95% CI)
All
Follow-up time, years
<3 131 678513 19.3 31 685753 4.52 4.26(2.88, 6.31)*** 3.99(2.69, 5.91)***
3-6 64 504262 12.7 22 512187 4.30 2.96(1.82, 4.80)*** 2.67(1.64, 4.35)***
>6 60 555167 10.8 34 568921 5.98 1.81(1.19, 2.75)** 1.74(1.14, 2.66)*
Ulcerative colitis (UC)
Follow-up time, years
<3 54 7.96 15 2.19 3.63(2.05, 6.44)*** 3.30(1.85, 5.88)***
3-6 32 6.35 11 2.15 2.96(1.49, 5.86)** 2.67(1.34, 5.34)**
>6 30 5.40 23 4.04 1.34(0.78, 2.30) 1.28(0.74, 2.22)
Crohn’s disease (CD)
Follow-up time, years
<3 77 11.4 16 2.33 4.85(2.83, 8.32)*** 4.58(2.67, 7.87)***
3-6 32 6.35 11 2.15 2.95(1.49, 5.86)** 2.65(1.33, 5.29)**
>6 30 5.40 11 1.93 2.80(1.40, 5.58)** 2.69(1.34, 5.40)**
Rate#: Incidence rate per 10 000 person-years; Crude HR: relative hazard ratio; Adjusted HR: adjusted hazard ratio after control for age, sex, and comorbidities of CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, and biliary stone; Comorbidity§: patients with CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, or biliary stone were classified as the comorbidity group. CAD, coronary artery disease; CI, confidence interval; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular disease; PY, person years; SD, standard deviation *P < .05, **P < .01, ***P < .001 Rate#: Incidence rate per 10 000 person-years; Crude HR: relative hazard ratio; Adjusted HR: adjusted hazard ratio after control for age, sex, and comorbidities of CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, and biliary stone; Comorbidity§: patients with CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, or biliary stone were classified as the comorbidity group. CAD, coronary artery disease; CI, confidence interval; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular disease; PY, person years; SD, standard deviation *P < .05, **P < .01, ***P < .001 Rate#: Incidence rate per 10 000 person-years; Crude HR: relative hazard ratio; Adjusted HR: adjusted hazard ratio after control for age, sex, and comorbidities of CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, and biliary stone; Comorbidity§: patients with CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, or biliary stone were classified as the comorbidity group. CAD, coronary artery disease; CI, confidence interval; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular disease; PY, person years; SD, standard deviation *P < .05, **P < .01, ***P < .001 Rate#: Incidence rate per 10 000 person-years; Crude HR: relative hazard ratio; Adjusted HR: adjusted hazard ratio after control for age, sex, and comorbidities of CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, and biliary stone; Comorbidity§: patients with CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, or biliary stone were classified as the comorbidity group. CAD, coronary artery disease; CI, confidence interval; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular disease; PY, person years; SD, standard deviation *P < .05, **P < .01, ***P < .001 Rate#: Incidence rate per 10 000 person-years; Crude HR: relative hazard ratio; Adjusted HR: adjusted hazard ratio after control for age, sex, and comorbidities of CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, and biliary stone; Comorbidity§: patients with CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, or biliary stone were classified as the comorbidity group. CAD, coronary artery disease; CI, confidence interval; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular disease; PY, person years; SD, standard deviation *P < .05, **P < .01, ***P < .001 Rate#: Incidence rate per 10 000 person-years; Crude HR: relative hazard ratio; Adjusted HR: adjusted hazard ratio after control for age, sex, and comorbidities of CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, and biliary stone; Comorbidity§: patients with CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, or biliary stone were classified as the comorbidity group. CAD, coronary artery disease; CI, confidence interval; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular disease; PY, person years; SD, standard deviation *P < .05, **P < .01, ***P < .001 Rate#: Incidence rate per 10 000 person-years; Crude HR: relative hazard ratio; Adjusted HR: adjusted hazard ratio after control for age, sex, and comorbidities of CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, and biliary stone; Comorbidity§: patients with CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, or biliary stone were classified as the comorbidity group. CAD, coronary artery disease; CI, confidence interval; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular disease; PY, person years; SD, standard deviation *P < .05, **P < .01, ***P < .001 Rate#: Incidence rate per 10 000 person-years; Crude HR: relative hazard ratio; Adjusted HR: adjusted hazard ratio after control for age, sex, and comorbidities of CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, and biliary stone; Comorbidity§: patients with CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, or biliary stone were classified as the comorbidity group. CAD, coronary artery disease; CI, confidence interval; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular disease; PY, person years; SD, standard deviation *P < .05, **P < .01, ***P < .001 Rate#: Incidence rate per 10 000 person-years; Crude HR: relative hazard ratio; Adjusted HR: adjusted hazard ratio after control for age, sex, and comorbidities of CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, and biliary stone; Comorbidity§: patients with CAD, hypertension, diabetes, hyperlipidemia, CVA, heart failure, COPD, CKD, alcohol-related diseases, cirrhosis, or biliary stone were classified as the comorbidity group. CAD, coronary artery disease; CI, confidence interval; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular disease; PY, person years; SD, standard deviation *P < .05, **P < .01, ***P < .001