Population laboratories with complete clinical information on episodes of care are needed to support research on the quality of care delivered to cancer patients. Data resources within the Cancer Research Network (CRN) may overcome many of the limitations of existing cancer databases, but their potential clinical value depends on the stability of the enrolled population. To assess this issue, we studied the retention rates among survivors of the 132 580 patients diagnosed with cancer from January 1, 1993, through December 31, 1998, who were enrolled at five health maintenance organization sites participating in the CRN. Enrollees were followed from cancer diagnosis through death, disenrollment, or the end of follow-up (i.e., December 31, 1999). The retention rate among survivors for all cancers combined at 1 and 5 years after cancer diagnosis was 96.0% (95% confidence interval [CI] = 95.9% to 96.1%) and 83.9% (95% CI = 83.4% to 84.3%), respectively. The proportion of enrollees diagnosed with cancer who remained enrolled and available for evaluation suggests that the CRN is well-suited for studies of the quality of care for cancer patients, survivorship, and long-term outcomes.

OBJECTIVE: To examine how estimates of osteoarthritis (OA) related health service utilization and medical care charges vary based on how the population of patients is defined, we compared a large cohort of patients identified through an administrative OA diagnosis relative to a subgroup of patients in whom this diagnosis had been validated through medical record review. METHODS: We identified all members (> or = 18 years of age) of a Massachusetts group model health maintenance organization (HMO) with documentation of at least one health care encounter associated with an OA diagnosis during the period 1994-96 (n = 10,740). From this population we randomly selected 700 subjects. Trained nurse reviewers abstracted relevant clinical, laboratory, and radiologic data from their medical records. Physician reviewers evaluated the abstracted information and rated the evidence for the presence of OA according to 3 levels (definite, possible, and unlikely). All persons rated by the physician reviewers as having definite OA were included in the validated subgroup (n = 442). Health service utilization and medical care charges were assessed in all persons with an administrative OA diagnosis who were not randomly sampled (n = 10,040) and the validated subgroup (n = 442) across the following domains: (1) ambulatory encounters associated with an OA diagnosis, (2) relevant radiographic studies, (3) relevant surgical procedures, and (4) relevant medication use. RESULTS: Those in the validated subgroup had higher rates of ambulatory OA associated health care encounters, radiographic studies, surgical procedures, and analgesic and/or antiinflammatory medication dispensings. Patients in the validated subgroup were significantly more likely to be in the highest quartile for total one year charges for the care of OA. CONCLUSION: Estimates of health service utilization are substantially higher for populations of patients in whom a diagnosis of OA has been validated through medical record review, as compared with unvalidated populations identified solely through diagnoses contained in administrative records. Thus using health service utilization estimates based on an unvalidated sample may lead to an inaccurate estimate when extrapolated to the overall population of patients with OA.

BACKGROUND: Treatment with glucocorticoids is the leading cause of drug-induced osteoporosis. Currently available guidelines indicate that patients receiving long-term glucocorticoid therapy should receive measures to prevent osteoporosis. OBJECTIVES: To examine whether patients receiving long-term glucocorticoid therapy in a managed care setting received preventive therapy or prescribed medications for osteoporosis and to identify patient and provider characteristics associated with treatment. SUBJECTS AND METHODS: A cohort of 224 health plan enrollees 20 years and older who were dispensed at least 1 oral glucocorticoid prescription per quarter during the period October 1997 through September 1998 was identified from administrative data. Medical charts and administrative data were reviewed to determine use of preventive therapy and prescribed medications for osteoporosis. RESULTS: Of the 224 patients, 62% had at least 1 documented intervention aimed at osteoporosis prevention (counseling about calcium or vitamin D or weight-bearing exercise; prescription for estrogen, calcitonin, or bisphosphonate; or a bone mineral density study). Women were more likely than men to receive intervention (76% vs 44%; prevalence odds ratio, 4.41; 95% confidence interval, 2.17-9.10). Patients receiving a mean daily prednisone dose of 10 mg or more or 5 to less than 10 mg were no more likely to receive intervention than those receiving 5 mg or less prednisone daily. Sixty-two (90%) of 69 patients who were prescribed glucocorticoid therapy by rheumatologists had at least 1 intervention documented compared with 29 (48%) of 60 for internists, 26 (55%) of 47 for pulmonologists, and 22 (46%) of 48 for all other physicians. In a multiple logistic regression model, including patient age, sex, mean daily glucocorticoid dose, and physician specialty, women and patients prescribed glucocorticoids by a rheumatologist were significantly more likely to receive intervention aimed at osteoporosis prevention. CONCLUSIONS: A substantial proportion of patients receiving long-term glucocorticoid therapy do not receive preventive therapy for osteoporosis. Efforts should be made to reduce barriers to such treatment and increase the proportion of patients given preventive therapy.

BACKGROUND: During the first year that the rhesus rotavirus tetravalent vaccine (RRV-TV) was licensed, the Vaccine Adverse Event Reporting System received several reports of intussusception after vaccination. To evaluate the risk of intussusception, we conducted a retrospective cohort study in ten managed care organizations. METHODS: Cases of intussusception were identified by searching electronic databases for diagnoses of intussusception (ICD-9 Code 560.0) in infants 1 to 11 months of age and confirmed by medical chart review. Vaccination and enrollment data were obtained from administrative databases. Incidence rate ratios (RR) of intussusception were computed by dividing incidence rates in prespecified risk intervals after vaccination by the background rate of intussusception and adjusted for age by Poisson regression. Cox proportional hazard regression was used to evaluate risk by vaccine dose. RESULTS: Of 463,277 children 56,253 had been vaccinated with a total of 91 371 doses of RRV-TV. The incidence rate of intussusception was 25/100,000 person years among unexposed infants and 340/100,000 person years 3 to 7 days postvaccination. In the interval 3 to 7 days after vaccination, the age-adjusted RR was 16.0 (95% confidence interval, 5.5 to 46.7) for all doses combined and 30.4 (95% confidence interval, 8.8 to 104.9) after the first dose. RRs for the 8- to 14- and 15- to 21-day risk intervals were >1.0, but the confidence intervals substantially overlapped 1.0. The attributable risk was one case of intussusception per 11 073 children vaccinated. CONCLUSIONS: RRV-TV is associated with an increased risk of intussusception. The risk is greatest 3 to 7 days after the first vaccination dose.

BACKGROUND: Formulary switches between agents in the same therapeutic class have become commonplace in the managed care setting as a strategy to reduce costs. OBJECTIVES: We evaluated the impact of a formulary switch from conjugated to esterified estrogen tablets at the Fallon Community Health Plan, a mixed-model health maintenance organization. DESIGN: A retrospective study was conducted with the use of the automated database of the health plan. SUBJECTS: Study subjects were members of the health plan during the period from May 1, 1995, to December 31, 1997, who were dispensed > or =1 estrogen replacement product. From this population, a cohort of users of conjugated estrogens during the period from May 1, 1995, to October 31, 1995, was selected. MEASURES: The cumulative incidence of switching from conjugated to esterified estrogen tablets and subsequent discontinuations of esterified estrogens was evaluated. The frequencies of ambulatory encounters during the 6 months before and after a switch or discontinuation were compared. RESULTS: During the period after promotion of the formulary switch, 2,149 of 2,984 patients (72%) originally dispensed conjugated estrogen tablets switched to esterified estrogen tablets. Among those patients switching to esterified estrogens, an excess of 20 office visits per 100 patients was noted in the postswitch period (P = 0.005). The risk of switching back to conjugated estrogen tablets was 15% by 2 years. CONCLUSIONS: The findings of this study suggest that plan efforts were successful in switching most users of conjugated estrogens to esterified estrogens. The switch was associated with an increase in utilization of health care services.

OBJECTIVE: To assess the positive and negative predictive values of osteoarthritis (OA) diagnoses contained in an administrative database. METHODS: We identified all members (> or =18 years of age) of a Massachusetts health maintenance organization with documentation of at least one health care encounter associated with an OA diagnosis during the period 1994-1996. From this population, we randomly selected 350 subjects. In addition, we randomly selected 250 enrollees (proportionally by the age and sex of the 350 subjects) who did not have a health care encounter associated with an OA diagnosis. Trained nurse reviewers abstracted OA-related clinical, laboratory, and radiologic data from the medical records of both study groups (all but 1 chart was available for review). Pairs of physician reviewers evaluated the abstracted information for both groups of subjects and rated the evidence for the presence of OA according to 3 levels: definite, possible, and unlikely. RESULTS: Among the group of patients with an administrative diagnosis of OA, 215 (62%) were rated as having definite OA, 36 (10%) possible OA, and 98 (28%) unlikely OA, according to information contained in the medical record. The positive predictive value of an OA diagnosis was 62%. In those without an administrative OA diagnosis, 44 (18%) were assigned a rating of definite OA. The negative predictive value of the absence of an administrative OA diagnosis was 78%. CONCLUSION: Use of administrative data in epidemiologic and health services research on OA may lead to both case misclassification and under ascertainment.