Principal components analysis of drug expenditure and utilisation trends for major therapeutic classes in US Medicaid programmes

Transferability of health cost evaluation across locations in oncology: cluster and principal component analysis as an explorative tool

Background

The transferability of economic evaluation in health care is of increasing interest in today’s globalized environment. Here, we propose a methodology for assessing the variability of data elements in cost evaluations in oncology. This method was tested in the context of the European Network of Excellence “Connective Tissues Cancers Network”.

Methods

Using a database that was previously aimed at exploring sarcoma management practices in Rhône-Alpes (France) and Veneto (Italy), we developed a model to assess the transferability of health cost evaluation across different locations. A nested data structure with 60 final factors of variability (e.g., unit cost of chest radiograph) within 16 variability areas (e.g., unit cost of imaging) within 12 objects (e.g., diagnoses) was produced in Italy and France, separately. Distances between objects were measured by Euclidean distance, Mahalanobis distance, and city-block metric. A hierarchical structure using cluster analysis (CA) was constructed. The objects were also represented by their projections and area of variability through correlation studies using principal component analysis (PCA). Finally, a hierarchical clustering based on principal components was performed.

Results

CA suggested four clusters of objects: chemotherapy in France; follow-up with relapse in Italy; diagnosis, surgery, radiotherapy, chemotherapy, and follow-up without relapse in Italy; and diagnosis, surgery, and follow-up with or without relapse in France. The variability between clusters was high, suggesting a lower transferability of results. Also, PCA showed a high variability (i.e. lower transferability) for diagnosis between both countries with regard to the quantities and unit costs of biopsies.

Conclusion

CA and PCA were found to be useful for assessing the variability of cost evaluations across countries. In future studies, regression methods could be applied after these methods to elucidate the determinants of the differences found in these analyses.

Electronic supplementary material

The online version of this article (doi:10.1186/s12913-014-0537-x) contains supplementary material, which is available to authorized users.

Utilization, Spending, and Price Trends for Benzodiazepines in the US Medicaid Program: 1991-2009

Background:

Although it is well-known that drug costs in the US have risen precipitously over the last 25 years, what is much less appreciated is how this rise in cost has occurred across so many seemingly distinct drug markets.

Objective:

To describe trends in the utilization, spending, and average per-prescription cost of benzodiazepines individually, in subgroups, and overall, in the Medicaid program. Medicaid has been the primary public payer for benzodiazepines over the past 2 decades.

Methods:

A retrospective, descriptive analysis was performed for the years 1991-2009 using the publicly available national Summary Files from the Medicaid State Drug Utilization Data maintained by the Centers for Medicare & Medicaid Services. Quarterly prescription counts and reimbursement amounts were calculated for all benzodiazepines reimbursed by Medicaid. Average per-prescription spending as a proxy for drug price was found by dividing reimbursement by the number of prescriptions.

Results:

Prescriptions for benzodiazepines among Medicaid beneficiaries increased from 8.0 million in 1991 to 17.1 million in 2009. Expenditures rose from $131.6 million to $171.1 million over the same time period. The average per-prescription price was a little over $10 in 2009. Whereas utilization of intermediate- and long-acting agents increased over time, prescriptions for short-acting drugs fell from 1.1 million to 0.3 million (1991-2009). The percentage rise in Medicaid spending on benzodiazepines since 1991 (30.0%) was less than the general rate of inflation (57.5%), as measured by the percentage change in the consumer price index over the same time period.

Conclusions:

Relative to the rise in the number of Medicaid beneficiaries (more than doubled over the study period), there is no evidence of an extraordinary rise in the utilization of benzodiazepines. Moreover, both nominal and real average prices of benzodiazepines have fallen, primarily because of generic entry over the last 2 decades.