Utilization of surveillance after polypectomy in the medicare population--a cohort study.
BACKGROUND
Surveillance in patients with previous polypectomy was underused in the Medicare population in 1994. This study investigates whether expansion of Medicare reimbursement for colonoscopy screening in high-risk individuals has reduced the inappropriate use of surveillance.


METHODS
We used Kaplan-Meier analysis to estimate time to surveillance and polyp recurrence rates for Medicare beneficiaries with a colonoscopy with polypectomy between 1998 and 2003 who were followed through 2008 for receipt of surveillance colonoscopy. Generalized Estimating Equations were used to estimate risk factors for: 1) failing to undergo surveillance and 2) polyp recurrence among these individuals. Analyses were stratified into three 2-year cohorts based on baseline colonoscopy date.


RESULTS
Medicare beneficiaries undergoing a colonoscopy with polypectomy in the 1998-1999 (n = 4,136), 2000-2001 (n = 3,538) and 2002-2003 (n = 4,655) cohorts had respective probabilities of 30%, 26% and 20% (p<0.001) of subsequent surveillance events within 3 years. At the same time, 58%, 52% and 45% (p<0.001) of beneficiaries received a surveillance event within 5 years. Polyp recurrence rates after 5 years were 36%, 30% and 26% (p<0.001) respectively. Older age (≥ 70 years), female gender, later cohort (2000-2001 & 2002-2003), and severe comorbidity were the most important risk factors for failure to undergo a surveillance event. Male gender and early cohort (1998-1999) were the most important risk factors for polyp recurrence.


CONCLUSIONS
Expansion of Medicare reimbursement for colonoscopy screening in high-risk individuals has not reduced underutilization of surveillance in the Medicare population. It is important to take action now to improve this situation, because polyp recurrence is substantial in this population.
Department of Public Health, Erasmus MC, Rotterdam, the Netherlands.
Iris
I
Lansdorp-Vogelaar
Surveillance & Health Services Research, Intramural Research Department, American Cancer Society, Atlanta, GA, United States of America; Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA, United States of America.
Stacey
S
Fedewa
Surveillance & Health Services Research, Intramural Research Department, American Cancer Society, Atlanta, GA, United States of America.
Chun Chieh
CC
Lin
Department of Health Policy and Management, Emory University, Atlanta, GA, United States of America.
Katherine S
KS
Virgo
Surveillance & Health Services Research, Intramural Research Department, American Cancer Society, Atlanta, GA, United States of America.
Ahmedin
A
Jemal
D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003106:Colon / Q000601:surgery; D003110:Colonic Neoplasms / Q000517:prevention & control; D003111:Colonic Polyps / Q000601:surgery*; D003113:Colonoscopy / Q000191:economics / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008403:Mass Screening / Q000191:economics*; D006278:Medicare / Q000191:economics / Q000706:statistics & numerical data*; D016017:Odds Ratio; D011159:Population Surveillance; D012008:Recurrence; D014481:United States