Impact of a Medicare MTM Program: Evaluating Clinical and Economic Outcomes | Page 2
Published Online: February 25, 2014
Rita L. Hui, PharmD, MS; Brian D. Yamada, PharmD; Michele M. Spence, PhD; Erwin W. Jeong, PharmD; and James Chan, PharmD, PhD
This study was a retrospective, matched-control cohort study. The study group consisted of KP members participating in the Medicare MTM program who had a comprehensive medication review and as-needed follow-ups conducted by an MTM pharmacist. The matched-control group consisted of KP members who were Medicare beneficiaries, who may or may not have been enrolled in MPD, and were not eligible for MTM. Since patients that qualified for MTM (1) were enrolled in MPD, (2) had higher medication costs, and (3) had high disease burden, a likely control patient did not have all 3 conditions and hence may have had less spending in medications and less disease burden. Both the study and the control groups received the usual care, with scheduled visits with their primary care physician or other healthcare providers. Each study group member was matched to 4 control group members based on geographic location, age (same birth year), gender, and prospective diagnostic-cost-group (DxCG) score (within ± 0.01).20 The DxCG score predicts an individual’s total healthcare cost in the next year relative to the population mean using a model based on age, gender, diagnoses, and drug codes. This relative score is calculated at the individual level. DxCG scores for Medicare beneficiaries ranged from .05 to 15.59 in the national population. Individuals with a score of 1.0 have a relative risk that is equivalent to that of the national Medicare reference population.
The study group was enrolled in MTM during the 5-year period between January 2006 and December 2010. They were followed from their enrollment date for 365 days, or until death, or disenrollment from the health plan, whichever came first. If members were enrolled in the MTM program for multiple years, only the first year of enrollment was included in the study. The matched controls for each MTM member were assigned the same enrollment date as the MTM member and were followed in the same way as the patients enrolled in the study group. Each study and control group member was unique and was only used once in this study. All subjects must have had continuous health plan membership with drug benefits during the 12 months prior to the study period to ensure complete pre-period data.
Exclusions included subjects with a cancer diagnosis within 1 year of study entry and nursing home residents. This was because cancer patients were being followed by the specialized oncology team, which included physicians, pharmacists, nurses and social workers at KP and patients residing in the nursing homes did not obtain prescription drugs from our internal KP outpatient pharmacies.
All data were obtained from KP’s integrated electronic medical, pharmacy, and administrative databases. Other covariables included: age, gender, Charlson Comorbidity Index (CCI),21 and pre-period utilization, including hospitalization, ED visits, and daily medication costs during the 12-month period prior to enrollment.
This study was approved by Kaiser Permanente Institutional Review Boards of both Northern and Southern California regions.
The primary outcome of this study was all-cause mortality within 365 days of study enrollment. Deaths were identified using several administrative and clinical data sources within KP, including records indicating discharge status after hospitalization. Deaths that occurred outside of the health plan were identified from California vital statistics death tapes. Secondary outcomes included percentage of hospitalization and ED visits within each group, and median change in prescription cost per day for the same period. Since some patients did not have 365 days of follow-up records due to death or termination of membership, prescription cost were assessed on a cost-per-day metric. Daily medication costs were calculated by dividing total medication costs by the length of follow up time during study period.
Descriptive statistics, including x2, t test, and Wilcoxon rank sum test, were used to compare baseline characteristics. In order to identify the direct impact MTM services had on the outcomes of interest, multiple logistic regressions were used to analyze proportion of patients who were hospitalized or who visited the ED; the Cox proportional hazards model was used to analyze death rate; and multiple ordinary least squares modeling was used to analyze changes in daily medication costs. Except for the Cox proportional hazards model, each model was adjusted for age, gender, region, CCI, and prior utilization of the same outcomes. All outcomes, except changes in daily medication costs, were analyzed as dichotomous variable. Changes in medication costs were analyzed as continuous variable. Test for proportional hazards assumption was assessed for the Cox proportional hazards models. Identical and separate analyses were done on study groups that were enrolled in 2010 because of the substantial changes in enrollment criteria. All analyses were performed using SAS 9.1.3 (SAS Institute, Cary, North Carolina).
During the study period from 2006 to 2010, a total of 46,734 MPD members had received an MTM comprehensive medication review. After applying the matching and exclusion criteria, 34,532 members receiving MTM services were identified and matched to 138,128 control members in a 1:4 ratio (Figure) based on age, gender, geographic location, and DxCG risk score. Over 81% of the members in both groups had a 1-year follow-up period. It represented 31,549 personyears in the study group and 124,546 person-years in the control group. Study enrollment rate was similar during 2006 to 2009, however, enrollment significantly increased in 2010, due to CMS-mandated changes, and these enrollees comprised 39% of the entire study cohort (MTM: 13,402; control: 53,608). The study population had a mean age of 75 ± 8 years, 58% were female, and the median DxCG score was 1.5 (IQR 0.8-2.5). Based on the 12-month data prior to enrollment to MTM services, the study group had a significantly higher CCI (a score that predicted the relative risk of death from prognostic clinical covariables), a higher rate of inpatient hospitalizations and ED usage, and higher daily medication costs than the matched controls (Table 1).
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