The Impact of Drug Price Adjustment on Prescribing Patterns in Different Pharmaceutical Market Competition Environment: A Longitudinal Analysis of Oral Anti-hyperglycemic Drugs
Date Issued
2011
Date
2011
Author(s)
Su, Hao-Jan
Abstract
Background
The Bureau of National Health Insurance in Taiwan uses drug price adjustment (DPA) to control the growth of pharmaceutical expenditures for years. However, they still grow up steadily and account for about 25% of total NHI medical expenditures. In addition to the increase of the patients with chronic diseases and the development of pharmaceutical technology, the association between physician''s behavior and incentives beyond the clinical field has been well-established. Nevertheless, few studies focused on the impact of different pharmaceutical market competition characteristics (PMCCs) while assessing the impact of DPA on the changes of physician''s prescription decisions. This study selected oral anti-hyperglycemic drugs (OADs) market to examine the relationship between PMCCs and the prescribing patterns in the period of DPA.
Objectives
1) To describe the trends of OADs prescribing pattern from 2002 to 2009 among different types of medical care institution visited, PMCCs, and hospital attributes. 2) To examine the effects of DPA on physician''s prescription decision in replacing drugs or adjusting dosage while taking different PMCCs into account.
Methods
Using the NHI claims data, we identified diabetic patients taking OADs every year from 2002 to 2009, and described the trends of their prescribing patterns, including average prescribed daily DDD amount per prescription, average DDD amount per prescription, and average lengths of one prescription. In the first part of the study, the patients were divided into 5 groups (A-E) by the types of medical care institution visited and we described their trends of prescribing patterns by different DCSI scores. Furthermore, patients in group A, that patients only visited their doctors in hospitals, were selected to examine the trend of prescription patterns while considering the three PMCCs (HHI, the number of firms, and the market size) levels and hospital attribute. In the second part of the study, we selected those who visited the physicians in the same hospitals with the same combination of OADs class and utilization rate of refillable prescriptions for chronic diseases during the period of drug price adjustment in group A. Finally we examined the relationship between PMCCs and the prescribing patterns in the period of two DPAs by GEE liner model.
Results
Within the study period, SUs and BGs were prescribed decreasingly. In the meanwhile, the amount of TZDs, AGIs and MGs increased slightly. The top 5 combinations of OADs class that account for more than 70% of all prescriptions were "BGs+SUs", "SUs", "BGs", "BGs+SUs+TZDs", and "BGs+SUs+AGIs". Combination therapy was more widely prescribed than monotherapy which was decreased from 40% to less than 30%. The regimen for two OAD classes account for over 50% in all prescriptions every year and the regiment for three OAD classes ranged from less than 10% to about 30%. DCSI scores of diabetic patients were increasing in the time period and those who didn’t have the regular medical care institution type increased most quickly.
Generally speaking, if patient''s medical care institution type was hospitals, the DCSI scores were higher. Moreover, we found if PMCCs were high competition, (including lower HHI, more firms, and bigger market size,) or if the hospital attributes were "medical center" or "proprietary hospital", prescribed daily DDD amount per prescription, DDD amount per prescription, and lengths of one prescription tended to be higher or longer. We also found that after DPA, the current drugs were likely to be replaced by other drugs that had lower adjustment magnitude. In addition, the dosage and lengths of one prescription tended to be higher or longer. Besides, in the low competition groups of PMCCs, the physicians replaced the drugs more frequently. However, in the high competition groups of PMCCs, the patient''s prescription dosage was increased more at the 3rd DPA, but not at the 5th DPA.
Conclusions
This study revealed that pharmaceutical competition level was associated with physician''s prescribing behavior. In general, when facing the drug price adjustment, the responding strategies of the hospitals were replacing the current drugs by other drugs that had lower adjustment magnitude and increasing the dosage. In addition, the changes of physician''s prescribing behavior differ when the PMCCs were considered. Based on the findings, the Bureau of National Health Insurance in Taiwan should investigate if the change of prescription patterns might result in poor treatment outcome after DPA. On top of that, they should monitor the increase of the dosage, especially in the hospitals with high pharmaceutical competition level, and evaluate the cost-effectiveness of higher dosage to ensure drug safety and prevent the unnecessary pharmaceutical expenditures.
The Bureau of National Health Insurance in Taiwan uses drug price adjustment (DPA) to control the growth of pharmaceutical expenditures for years. However, they still grow up steadily and account for about 25% of total NHI medical expenditures. In addition to the increase of the patients with chronic diseases and the development of pharmaceutical technology, the association between physician''s behavior and incentives beyond the clinical field has been well-established. Nevertheless, few studies focused on the impact of different pharmaceutical market competition characteristics (PMCCs) while assessing the impact of DPA on the changes of physician''s prescription decisions. This study selected oral anti-hyperglycemic drugs (OADs) market to examine the relationship between PMCCs and the prescribing patterns in the period of DPA.
Objectives
1) To describe the trends of OADs prescribing pattern from 2002 to 2009 among different types of medical care institution visited, PMCCs, and hospital attributes. 2) To examine the effects of DPA on physician''s prescription decision in replacing drugs or adjusting dosage while taking different PMCCs into account.
Methods
Using the NHI claims data, we identified diabetic patients taking OADs every year from 2002 to 2009, and described the trends of their prescribing patterns, including average prescribed daily DDD amount per prescription, average DDD amount per prescription, and average lengths of one prescription. In the first part of the study, the patients were divided into 5 groups (A-E) by the types of medical care institution visited and we described their trends of prescribing patterns by different DCSI scores. Furthermore, patients in group A, that patients only visited their doctors in hospitals, were selected to examine the trend of prescription patterns while considering the three PMCCs (HHI, the number of firms, and the market size) levels and hospital attribute. In the second part of the study, we selected those who visited the physicians in the same hospitals with the same combination of OADs class and utilization rate of refillable prescriptions for chronic diseases during the period of drug price adjustment in group A. Finally we examined the relationship between PMCCs and the prescribing patterns in the period of two DPAs by GEE liner model.
Results
Within the study period, SUs and BGs were prescribed decreasingly. In the meanwhile, the amount of TZDs, AGIs and MGs increased slightly. The top 5 combinations of OADs class that account for more than 70% of all prescriptions were "BGs+SUs", "SUs", "BGs", "BGs+SUs+TZDs", and "BGs+SUs+AGIs". Combination therapy was more widely prescribed than monotherapy which was decreased from 40% to less than 30%. The regimen for two OAD classes account for over 50% in all prescriptions every year and the regiment for three OAD classes ranged from less than 10% to about 30%. DCSI scores of diabetic patients were increasing in the time period and those who didn’t have the regular medical care institution type increased most quickly.
Generally speaking, if patient''s medical care institution type was hospitals, the DCSI scores were higher. Moreover, we found if PMCCs were high competition, (including lower HHI, more firms, and bigger market size,) or if the hospital attributes were "medical center" or "proprietary hospital", prescribed daily DDD amount per prescription, DDD amount per prescription, and lengths of one prescription tended to be higher or longer. We also found that after DPA, the current drugs were likely to be replaced by other drugs that had lower adjustment magnitude. In addition, the dosage and lengths of one prescription tended to be higher or longer. Besides, in the low competition groups of PMCCs, the physicians replaced the drugs more frequently. However, in the high competition groups of PMCCs, the patient''s prescription dosage was increased more at the 3rd DPA, but not at the 5th DPA.
Conclusions
This study revealed that pharmaceutical competition level was associated with physician''s prescribing behavior. In general, when facing the drug price adjustment, the responding strategies of the hospitals were replacing the current drugs by other drugs that had lower adjustment magnitude and increasing the dosage. In addition, the changes of physician''s prescribing behavior differ when the PMCCs were considered. Based on the findings, the Bureau of National Health Insurance in Taiwan should investigate if the change of prescription patterns might result in poor treatment outcome after DPA. On top of that, they should monitor the increase of the dosage, especially in the hospitals with high pharmaceutical competition level, and evaluate the cost-effectiveness of higher dosage to ensure drug safety and prevent the unnecessary pharmaceutical expenditures.
Subjects
Oral anti-hyperglycemic drugs
Prescribing patterns
Drug price adjustment
Pharmaceutical market competition
Type of medical care institution visited
SDGs
Type
thesis
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