Rapid Penetration of COX 2 Inhibitors in NonSteroidal
Rapid Penetration of COX 2 Inhibitors in Non-Steroidal Antiinflammatory Drug Market: an Implication to Hospital Cost Containment Policy Supon Limwattananon, MPHM, Ph. D * Chulaporn Limwattananon, MPharm, MSc, Ph. D * Supasit Pannarunothai, MD, Ph. D ** * Faculty of Pharmaceutical Sciences, Khon Kaen University ** Center for Health Equity Monitoring, Naresuan University - Thailand
Abstracts Problem Statement: Since their 1999 launch claiming few gastrointestinal side effects, cyclo-oxygenase-2 (COX 2) inhibitors have become a market competitor with conventional non-steroidal antiinflammatory drugs (NSAIDs. ( Objectives: To examine variations in NSAID expenditures as related to the use of COX 2 inhibitors and to assess patterns of drug channeling in the hospital drug market. Design: Retrospective, secondary analysis of electronic drug use databases. Setting and Population: Eighteen provincial hospitals in Thailand. A total of 1, 558, 633 prescriptions for oral NSAID solid dosage forms given to ambulatory patients from 2000 to 2002. Outcome Measures: Total and per patient, quarterly and annual expenditures in Thai Baht; % of expenditures and prescriptions for COX 2 inhibitors; number of daily doses of drugs prescribed; odds ratios (OR) for receiving COX 2 inhibitors. Results: In total, NSAID expenditures increased by 47. 6% from 23. 2 million Baht in 2000 to 34. 3 million Baht in 2001, then increased slightly after implementation of Universal Health Care Coverage (UC) scheme to 38. 0 million Baht in 2002. Part of this rapid growth was driven by pricing. Expenditures for COX 2 inhibitors increased dramatically from 6. 5% in the first quarter of 2000 to 52. 1% in the last quarter of 2002, and the prescription share gradually increased from 0. 5% to 4. 6% during the same period. Use of COX 2 inhibitors rather than other NSAIDs would raise the annual expenditures person as much as 1, 101. 2% (P<0. 001), using a generalized linear model. The utilization components did not show a consistent pattern across health insurance schemes of drug recipients. Based on logistic regression analysis, patients covered by the Civil Servant Medical Benefit Scheme (CSMBS) were 9. 7 -13. 2 and 15. 6 -23. 1 times (P<0. 001) more likely to receive COX 2 inhibitors in a year than Social Security Scheme (SSS) and UC beneficiaries, respectively. An analysis of the intensity-of-use component for the NSAID recipients who visited the hospitals in three consecutive years revealed a relatively longer period of COX 2 inhibitor use for CSMBS patients as compared to the patients in SSS and UC schemes. Conclusions: Growth in NSAID expenditures was largely driven by rapid penetration of the expensive COX 2 inhibitors. The prime target for these patent-protected, single-source products was fee-for-service schemes like CSMBS. To contain hospital drug costs with a generic substitution for COX 2 inhibitors is unfeasible due to the market exclusivity of the drugs. Therapeutic substitution with the multi-source NSAID seems to be a viable alternative in curbing NSAID expenditure growth.
Objectives 1. To examine variations in hospital NSAID expenditures as related to the use of COX 2 inhibitors 2. To assess patterns of drug channeling for COX 2 inhibitors Design and Analysis Retrospective, secondary analysis of electronic databases Settings 18 MOPH-provincial hospitals in 4 regions of Thailand Sample 1, 558, 633 prescriptions for oral NSAID solid forms rendered to ambulatory patients during fiscal years 2000 - 2002 Statistical analysis • For drug expenditures: a generalized linear model (GLM( • For propensity of drug use: logistic regression analysis Control for the underlying differences in drug use patterns due to • age groups and gender • years of drug use (and interaction with health insurance schemes) • hospital settings (proxy for variations in prescribing practice styles)
Rxs Number of Prescriptions for NSAID 2. 6% 4. 0% 4. 6% 0. 5% COX 2 inhibitors Other NSAID-NED Meloxicam Other NSAID-ED
Baht Expenditures by types of NSAID COX 2 inhibitors 33. 9% 6. 5% 46. 5% 52. 1% Other NSAID-NED Meloxicam Other NSAID-ED
Factors Affecting NSAID Expenditures per Capita (Competing Models( Model with interaction terms Coefficienta P value Main effect model Coefficienta P value COX 2 inhibitors 2. 486 < 0. 001 2. 488 < 0. 001 Age 36 – 49 years b 0. 368 < 0. 001 0. 370 < 0. 001 Age 50+ years b 0. 798 < 0. 001 0. 805 < 0. 001 - 0. 158 < 0. 001 0. 864 < 0. 001 0. 847 < 0. 001 Male CSMBS c LIC/UC c - 0. 001 0. 954 - 0. 053 < 0. 001 ROP c - 0. 022 0. 188 - 0. 084 < 0. 001 Year 2001 d - 0. 035 0. 065 0. 038 < 0. 001 Year 2002 d 0. 186 < 0. 001 0. 025 0. 002 CSMBS x Year 2001 0. 083 0. 002 CSMBS x Year 2002 - 0. 093 < 0. 001 LIC/UC x Year 2001 0. 123 < 0. 001 LIC/UC x Year 2002 - 0. 205 < 0. 001 ROP x Year 2001 0. 070 0. 002 ROP x Year 2002 - 0. 249 < 0. 001 a Based on generalized linear model (GLM) using log link, gamma distribution , adjusted for hospital indicators b Age of 18 -35 years as the reference category c SSS as the reference category d Year 2000 as the reference category
Effects on Difference in NSAID Expenditure % difference a 95% CI COX 2 inhibitors vs. other NSAID 1, 101. 2% 1, 056. 5 to 1, 147. 6% Age 36 -49 years 44. 5% 42. 3 to 46. 7% Age 50+ years vs. 18 -35 years 122. 0% 118. 5 to 125. 6% Male -14. 6% - 15. 7 to -13. 5% vs. 18 -35 years vs. Female a % difference due to an indicator variable = exp(Coefficient) - 1
Effects on Difference in NSAID Expenditure (Trends for Each Scheme( % difference a Year 2001 vs. LIC/UC SSS ROP CSMBS 9. 2% -3. 4% 3. 5% 4. 9% -1. 9% 20. 4% -6. 1% 9. 7% Year 2000 Year 2002 vs. Year 2000 a % difference due to an indicator variable = exp(Coefficient) - 1 Based on GLM with interaction of schemes and years
Effects on Difference in NSAID Expenditure (Comparison between Schemes for Each Year( % difference a Year 2000 Year 2001 Year 2002 137. 2% 157. 7% 116. 1% ROP vs. SSS -2. 2% 4. 9% -23. 7% LIC/UC vs. SSS -0. 1% 13. 0% -18. 6% CSMBS vs. SSS a % difference due to an indicator variable = exp(Coefficient) - 1 Based on GLM with interaction of schemes and years
Propensity to Receive COX 2 Inhibitors (Competing Models( Model with interaction terms Coefficienta P value Main effect model Coefficienta P value Age 36 – 49 years b 0. 619 < 0. 001 0. 617 < 0. 001 Age 50+ years b 1. 267 < 0. 001 1. 270 < 0. 001 - 0. 302 < 0. 001 - 0. 301 < 0. 001 2. 279 < 0. 001 2. 434 < 0. 001 Male CSMBS c LIC/UC c - 0. 845 < 0. 001 - 0. 585 < 0. 001 ROP c - 0. 407 < 0. 001 0. 178 < 0. 001 1. 105 < 0. 001 1. 200 < 0. 001 1. 145 < 0. 001 1. 512 < 0. 001 CSMBS x Year 2001 - 0. 009 0. 936 CSMBS x Year 2002 0. 303 0. 003 LIC/UC x Year 2001 0. 367 0. 009 LIC/UC x Year 2002 0. 285 0. 038 ROP x Year 2001 0. 461 < 0. 001 ROP x Year 2002 0. 853 < 0. 001 Year 2001 d Year 2002 d a Based on logistic regression analysis, adjusted for hospital indicators Age of 18 -35 years as the reference category c SSS as the reference category d Year 2000 as the reference category b
Odds* (in log scale( Odds of Receiving COX 2 Inhibitors CSMBS SSS ROP LIC/UC *Odds = exp(constant+b. Age+b. Gender+b. Scheme+b. Year+b. Schemex. Year+b. Hosp(
Odds Ratio of Receiving COX 2 Inhibitors (Comparison between Schemes for Each Year( Odds Ratio a Year 2000 CSMBS vs. LIC/UC Year 2001 Year 2002 22. 74 15. 62 23. 14 CSMBS vs. SSS 9. 77 9. 68 13. 22 ROP vs. LIC/UC 1. 55 1. 70 2. 73 LIC/UC vs. SSS 0. 43 0. 62 0. 57 a Based on logistic regression model with interaction of schemes and years
Conclusion • Growth in NSAID expenditures was largely driven by rapid penetration of the expensive COX 2 inhibitors. • The prime target for the patent-protected, single-source drugs was patients covered by fee-for-service scheme like CSMBS. • To contain hospital drug costs, a generic substitution for COX 2 inhibitors is unfeasible due to market exclusivity nature. • Therapeutic substitution with the multi-source NSAID is a viable alternative in curbing the expenditure growth.
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