Predicting Adherence to Colonoscopy or Flexible Sigmoidoscopy on the Basis of Physician AppointmentKeeping Behavior

Context Flexible sigmoidoscopy and colonoscopy are important screening tools for colon cancer, but many patients miss scheduled appointments for these procedures. Contribution In a large health care system in Philadelphia, 62% of 11 803 patients attended scheduled colon studies. Among patients who kept more than 85% or fewer than 66% of their scheduled visits with physicians in the past 2 years, 70% and 52%, respectively, attended the colon study appointment. Implications Patients who frequently miss scheduled appointments with their physicians will probably miss appointments for sigmoidoscopy and colonoscopy. The Editors Experts have endorsed periodic direct visualization of the colorectum to screen for colorectal cancer (1, 2). However, in 2001 the Behavioral Risk Factor Surveillance System found that less than half of eligible persons (48%) 50 years of age or older had had colonoscopy or flexible sigmoidoscopy (3). Endoscopic studies of the colorectum are particularly taxing for patients because they require substantial preparation, as well as keeping the appointment. We hypothesized that patients who were generally nonadherent to physician visits would also be less likely to keep their appointments for colon studies. Computerized scheduling data can now be used to evaluate patients' appointment-keeping behavior. These data may help to identify patients in greatest need of interventions to improve adherence to colonoscopy and flexible sigmoidoscopy. Methods Study Sample We used the University of Pennsylvania Health System's ambulatory scheduling and billing system (IDX Systems Corp., Burlington, Vermont) to identify all patients with flexible sigmoidoscopy or colonoscopy (colon study) scheduled by a primary care practice from June 1999 through November 2001. To focus on the first colon study, we considered only patients without a previous colon study since the scheduling system began in December 1997. Referring primary care practices ranged from large urban clinics and physician practices to small suburban physician practices. Sites performing these endoscopic procedures used various approaches to remind patients about scheduled studies, but there were several commonalities. All sites reminded patients by telephone before the procedure and mailed brochures about the preparation and the procedure. Patients who canceled their appointments could reschedule them immediately. Primary care physicians were not routinely notified when patients did not keep colon study appointments, but the scheduling system would have indicated this. Outcome Variables Our primary outcome was having arrived at the colon study appointment compared with cancellation or not showing up. For both the colon study appointment and physician visits, the patient was judged to have kept an appointment if a cancellation was followed by an arrival within 1 day. Among those patients who did not arrive but rescheduled within 6 months, our secondary outcome was arrival at the second appointment. We used the scheduling information from the IDX system from January 2000 through August 2002 to examine the disposition of follow-up colon studies. Primary Predictor Variable We examined all scheduled physician visits to both primary care and subspecialty physicians in the health system up to 2 years before the first colon study appointment to define physician visit adherence. Physician visit adherence was measured as the proportion of all scheduled physician appointments within 2 years preceding the first colon study appointment that had an arrived status. Study participants had a median of 13 scheduled visits to health system providers over a 2-year period (interquartile range, 7 to 25 visits), and the median proportion of visits that were kept was 75% (interquartile range, 65% to 86%). We created variables for quartiles of scheduled visits in the study time frame. Other Study Variables Because Asian and Hispanic persons made up only 4% of the sample, they were analyzed with white persons. Insurance type was classified as Medicare, Medicaid, commercial, or other (self-pay or unknown). From the 2000 U.S. Census, we determined the median household income associated with the ZIP code of each patient's residence. Missing data for race or ethnicity (n = 1033), ZIP code (n = 10), and median household income information for the ZIP code (n = 310) was imputed by using multiple imputation (4) in the SAS procedures PROC MI and PROC MIANALYZE (SAS Institute, Inc., Cary, North Carolina). We created an indicator for a chronic medical condition identified by 2 occurrences of coded diagnoses on inpatient or outpatient encounters: hypertension, diabetes mellitus, chronic obstructive heart disease, chronic bronchitis, asthma, coronary artery disease, congestive heart failure, peripheral vascular disease, cancer (lung, breast, uterus, prostate, or ovarian), and renal failure (available upon request). We also created an indicator for at least 2 occurrences of coded diagnoses for any chronic gastrointestinal conditions (available upon request). The 23 practices (primarily gastroenterology) where the procedures were scheduled were classified by urban versus suburban location. Finally, we created a variable for the 6-month time period in which the first colon study was scheduled. Statistical Analysis We examined unadjusted and adjusted associations of patients' adherence to physician visits with attending the first colon study appointment and, among nonattendees, with attending a rescheduled appointment within 6 months. Unadjusted analyses were performed by using the chi-square test. In all our adjusted analyses, conditional logistic regression was used to control for confounding because of clustering of patients in sites performing the endoscopic procedures. The clustering of similar patients in the study center is not addressed directly by conventional methods, such as generalized estimating equations or random-effects models. The variable for urban versus suburban practice location was not included in the conditional logistic regression model because it did not vary with the clustering variable (that is, practice). We also examined adjusted associations of patient characteristics with low physician visit adherence. Analyses were performed by using SAS software, version 8.0. Results For the 13 142 identified patients with a first colon study appointment from June 1999 through November 2001, we excluded patients with fewer than 3 physician visits in the preceding 2 years (n = 1258) because having few visits limited our examination of physician visit adherence. Other exclusions included death within study time frame (n = 73), missing sex data (n = 2), and no arrived visits to yield clinical data (n = 6). Persons with few physician visits had slightly higher adherence to the first colon study (64%) than did study participants (61%). Our final study sample included 11 803 persons with 228 577 scheduled visits to system providers and had procedures scheduled at 23 sites. Of these sites, 5 had fewer than 10 patients scheduled and 17 had more than 20 patients scheduled. Only 62% of the 11 803 study patients kept their first colon study appointment (Table 1). Of the 4496 nonattendees, 61% rescheduled within 6 months and, of these, 64% kept the second appointment. Adherence to physician visits was linearly associated with colon study adherence. Of patients in the lowest quartile of physician visit adherence (that is, those who kept 65% of visits), roughly half attended their first colon study compared with 70% of persons in the highest adherence level (that is, those who kept >85% of visits). Female sex; black race or ethnicity; median annual household income less than $25 000; chronic disease; and Medicaid, self-pay, or unknown insurance were negatively associated with keeping the first or the rescheduled colon study appointment. A gastrointestinal condition, colonoscopy, and a suburban gastroenterology practice had statistically significantly higher proportions of patients attending the first colon study. Table 1. Patient Demographic, Clinical, and Health Care Use Characteristics by Completion of First Scheduled Colon Study and, among Nonattendees, by Completion of a Rescheduled Study After adjustment, patient demographic characteristics were no longer predictive of colon study adherence (Table 2). A gastrointestinal condition was still statistically significantly associated with greater colon study adherence. Persons keeping 65% or fewer physician visits were 26% less likely to attend their first colon study than the highest quartile (>85% of visits kept). The 2 lowest quartiles of physician visit adherence both had statistically significantly lower adjusted odds of keeping the colon study appointments. This association did not change in a second model, which included only patients without a gastrointestinal diagnosis (n = 10 189) (data not shown). Persons who rescheduled (n = 2739) differed significantly from those who did not (n = 1757) only in regard to race or ethnicity (32% black vs. 38% other race or ethnicity; P < 0.001), lower neighborhood income (P < 0.001), and colonoscopy test scheduled (63% vs. 56%, respectively; P < 0.01). In a model predicting arrival at a rescheduled appointment (Table 2), the lowest quartile of physician visit adherence was the only variable statistically significantly associated with adherence. Table 2. Adjusted Associations of Patient, Practice, and Procedure Characteristics with Completing First Scheduled (n= 11 803) Colon Study Appointment or among Those Rescheduling within 6 Months (n= 2739) Keeping the Second Colon Study Appointment In a conditional logistic regression model examining predictors of poor physician visit adherence ( 65%) that included 25.6% of the original study sample, poor adherence was more likely (P < 0.01) for persons younger than 65 years of age than for those 70 years of age or older. The highest adjusted odds were for