Table 4 Outcome variables, results and limitations of ex-ante studies

Chaudhuri, Goldberg, & Gia [16]

Impact of patent enforcement on consumer surplus, profits and social welfare in the quinolone product market in India.

The total annual welfare losses to the Indian economy due to stringent patent laws in the quinolone sub-segment would be on the order of Rs. 20.16 billion or US$450 million.

Data range used to estimate the demand and supply parameters are from 1999 and 2000 and needs to be updated to obtain more accurate measures. The estimated demand elasticities are some proxies of real demand elasticities.

Elasticities are estimated using a reduced form demand system rather than estimating structurally. Further, assumes households are homogeneous in terms of income. Certainly, this assumption is not realistic

Dutta [2]

Impact of patent enforcement on prices, consumer surplus, profits and social welfare in 43 medicines market in India.

Profits for the patent holding firms increases from 0 to 3412% due to patent enforcement.

Data range used to estimate the demand and supply parameters are from 2001 and 2003 so data needs to be closer to 2005 to have better measure of elasticities and welfare.

Demand estimation does not include some important variable such as income of consumers. This implies that the elasticities are the same across different income levels, which is not a realistic assumption.

Akaleephan et al. [17]

Impact of data exclusivity on the accessibility, prices and total cost savings in 74 out of 1136 International Non-proprietary Name (INN) imported medicines in Thailand.

Consumption volume would be lower by 34.9% without generics

This paper uses only public sector data and since public sector might have higher bargaining power and costs of medicine for public sector are expected to very different from costs of medicine in private sector,

A simple linear regression is used to estimate market share following the generic entry. This simple linear regression would be biased due to omitting many important factors, which will also give biased estimates of cost savings.

Azam [18]

Impact of patent enforcement on sales, demand and prices in pharmaceutical sector in Bangladesh.

77% of surveyed executives of pharmaceutical firms either agreed (54%) or strongly agreed (23%) that the prices of medicines have increased and will go up further as a result of TRIPS compliance.

Data points used in trend analysis have at least 10 years’ interval, so by comparing price changes will not lend any sensible conclusion.

Trend analysis with large interval is not a rigorous way to find the effect of TRIPS provisions on medicine prices, many confounding factors can influence medicine prices.

Chaves et al. [19]

Impact of patent extension and data exclusivity on expenditure of HIV/AIDS and Hepatitis C medicines in Brazil.

Under the scenario that patent extension and 8 years’ data exclusivity are both adopted as proposed by EU, the ARV expenditure will increase by 69% and the expenditure on Hepatitis C will increase by more than 3000% in 35 years.

Simulations of alternative scenarios only considers the present average growth rate of expenditure on these two types of medicines, however, other factors such as change in demographics and disease prevalence rate would significantly affect the expenditure on these medicines.

Kessomboon et al. [20]

Impact of patent and data exclusivity extension on quantity and expenditure of all active ingredients in Thailand

Combining 10 years of patent extension with 5 years of delayed generic entry due to data linkage and 10 years of delayed generic entry due to data exclusivity will increase price index by 67%, expenditure to 23.6 billion USD over a 20 year period.

Outcome variable ‘expenditure’ is calculated by assuming a constant annual consumption growth of 12%, using actual expenditure for all the available years to calculate consumption growth would increase the precision of expenditure projection.

Projection does not consider other factors such income or population growth or change in demographics that might significantly change demand for medicines and hence the prices.