Browsing by Subject "Medication possession ratio"
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Item Examining adherence with medications used in treating diabetic peripheral neuropathic pain(2010-08) Oladapo, Abiola Oluwagbenga; Barner, Jamie C.; Rascati, Karen L.; Strassels, Scott A.The present study is a retrospective cohort analysis which sought to examine adherence to medications used in managing painful diabetic peripheral neuropathy (PDPN) and to determine their association with oral antidiabetic (OAD) medication adherence using the Texas Medicaid prescription claims database. The study objectives were to: 1) provide a description of PDPN and OAD medication use among the study subjects; 2) determine if PDPN medication adherence differs among individual PDPN agents (i.e., tricyclic antidepressants, gabapentin, pregabalin and duloxetine); 3) determine if pre-index OAD and post-index OAD medication adherence differs among mono, dual, and triple OAD therapies; and 4) determine if PDPN medication adherence is related to post-index OAD medication adherence while controlling for covariates. Study participants were adult (≥18 years) Medicaid beneficiaries prescribed OAD and PDPN medications. The index date was the first PDPN prescription. Data were extracted from June 1, 2003 to October 31, 2009 and prescription claims were analyzed over an 18-month study period (i.e., 6 months pre-index and 12 months post index period). Medication possession ratio (MPR) was used as a proxy measure of medication adherence. An MPR less than 80 percent was regarded as being non-adherent to prescribed medication, while an MPR greater than or equal to 80 percent was regarded as being adherent to prescribed medication. Objective 1 was addressed using descriptive statistics (i.e., mean, standard deviation, frequency). Univariate analysis (ANOVA) was employed to address Objectives 2 and 3. Multivariate analyses (i.e., multiple linear regression and logistic regression) were conducted to address Objective 4. For the logistic regression MPR was dichotomized at the cut-off value of 80 percent. A total of 4,277 patients met the study’s inclusion criteria. The overall mean MPR (±SD) for PDPN medications was 75.4 percent (±23.9). Mean MPR (±SD) was highest for duloxetine (85.6% ±18.2) and was lowest for pregabalin (69.4% ±24.9). Mean MPR differed significantly among individual PDPN medications (p<0.0001). The overall mean MPR (±SD) for OAD medications in the pre and post-index period was 73.0 percent (±24.3) and 64.5 percent (±25.6) respectively. In both pre and post-index periods, mean MPR differed significantly among mono, dual, and triple OAD therapies (p<0.0001). In the pre-index period, mean MPR (±SD) was highest for monotherapy users (75.4% ±24.7) and was lowest for triple therapy users (63.9% ±22.9). Similarly, mean MPR (±SD) was highest for monotherapy users (69.0% ±26.1) and was lowest for triple therapy users (52.9% ±21.8) in the post-index period. After controlling for the covariates, PDPN adherence (i.e., MPR) was statistically significant (p<0.0001) and positively related to post-index OAD adherence (i.e., MPR). PDPN patients who were non-adherent (i.e., MPR<80%) to their PDPN medications (or neuropathic pain medications), compared to those who were adherent (MPR≥80%), were significantly less likely to be adherent to their OAD medications [Odds Ratio (OR) = 0.626, 95% CI=0.545-0.719]. In addition, post-index OAD adherence (i.e., MPR) did not differ significantly (p>0.05) when pregabalin, duloxetine and gabapentin users were individually compared to tricyclic antidepressants users. In conclusion, PDPN patients who were adherent (i.e., MPR≥80%) to their PDPN medications, compared to those who were not adherent (i.e., MPR<80%), were more adherent to their OAD medications. Also, adherence to OAD medications was independent of the type of PDPN medication used. PDPN patients need to be educated regularly that neuropathic pain medications only relieve the pain associated with the neuropathy but achieving adequate glycemic control remains the only established approach for slowing down the progression of the neuropathy and other complications associated with the diabetes.Item Impact of Medicare part D on adherence and persistence to statin medications for Texas dual-eligible beneficiaries(2010-05) Richhariya, Akshara; Shepherd, Marvin D.; Lawson, Kenneth A.; Richards, Erika K.Statins are commonly used for treating the elevation of lipids in the blood stream, also known as hyperlipidemia. Statins are considered to be an economical and effective way to achieve desirable long-term health outcomes for hyperlipdemic patients, however, ensuring adequate adherence to statin medications is often difficult as hyperlipidemia is an asymptomatic condition and patients sometimes fail to recognize the importance of being adherent to their statin medications. The purpose of this study was to evaluate impact of enrollment under Medicaid and Medicare Part D and patient out-of-pocket costs on patient statin adherence, persistence, and mean number of gap days per claim. A retrospective claims database was used in this study to conduct repeated measures analyses on statin prescription claims from independent community pharmacies in Texas. The pre-period in this study extended from January 1, 2005 to September 30, 2005 (Medicaid period) and the post-period extended from January 1, 2006 to September 30, 2006 (Medicare period). The study population consisted of dual-eligible beneficiaries in Texas who had at least two stain claims in the pre and post-periods each. The final study population comprised of 1734 Texas dual-eligible beneficiaries with 6064 statin claims during the pre-period and 7956 claims during the post-period. Patients had an average of 3.49 statin claims during the pre-period and 4.58 statin claims during the post-period. Patients were dispensed an average of 57.34 days of drug supply per claim during the pre-period and 42.02 days of drug supply per claim during the post-period. The results from this study showed that out-of-pocket costs for patients increased from $0.39 per claim under Medicaid to $13.36 per claim under Medicare Part D. Patient adherence to statins was assessed by calculating medication possession ratio (MPR). The results showed that mean patient MPR increased from 75.71 percent under Medicaid to 79.37 percent under Medicare. Results from generalized estimating equations showed that odds of being adherent (i.e., MPR ≥ 80 percent) to statins increased by 36 percent when patients were covered under Medicare Part D. Linear mixed model analysis showed that MPR increased by 3.66 percent when patients were covered under Medicare Part D compared to Medicaid. Also, patient MPR was found to increase by 0.13 percent when patient out-of-pocket payment increased by $1.00. Patient persistence was calculated by measuring gaps in therapy and patients with a gap of 60 or more days were considered to have discontinued therapy. Patients were found to be persistent to their drug therapy for an average of 151.76 days under Medicaid and 159.75 days under Medicare. Linear mixed model analysis showed that patient persistence increased by 7.99 days when patients were enrolled under Medicare Part D compared to Medicaid. Days of persistence was also found to increase by 0.41 days when patient out-of-pocket costs increased by $1.00. Mean number of gap days per claim during the Medicaid period was 11.91 days and decreased to 8.38 days during the Medicare period. Linear mixed model analysis showed that mean number of gap days per claim decreased by 3.52 days when patients were enrolled under Medicare Part D compared to Medicaid. Mean number of gap days in therapy were found to decrease by 0.10 days when patient out-of-pocket costs increased by $1.00. The results of this study showed that implementation of Medicare Part D resulted in an increase in MPR and persistence and a decrease in mean number of gap days per claim for Texas dual-eligible beneficiaries. The results also suggest that increased out-of-pocket costs under Medicare Part D may not have had a negative impact on statin drug utilization by dual-eligible beneficiaries in Texas.