Emergence of New Drugs for Intractable Diseases is Associated with an Increase in the Number of Patients Diagnosed Thereafter with Those Intractable Diseases.

Background: Estimates of the prevalence of diseases can be affected by changes in the awareness of the diseases. The emergence of new drugs may affect the awareness of the diseases among patients and physicians. We have reported that the rate of increase in the number of drugs available was a statistically significant factor correlated with the rate of increase in the number of patients diagnosed thereafter. We aimed to investigate the impact of the emergence of new drugs on the number of patients diagnosed with individual intractable diseases and to determine the types of drugs that had a greater impact on these changes. Methods: The number of patients, the number of drugs indicated and diagnostic and certification criteria for the diseases from 2004 to 2013 were collected from publicly available data. We compared the annual rate of increase in the number of patients before and after the emergence of new drugs. Factors affecting the annual rate of increase in the number of patients were investigated. Results: The annual rate of increase in the number of patients was statistically significantly increased after the emergence of new drugs (Average increase of 0.9% per year, Wilcoxon signed-rank test; p = 0.035). The emergence of drugs with new active substances and drugs with new mechanisms of action were statistically significant factors correlated with the increase in the number of patients. Conclusion: The emergence of new drugs, especially drugs with new active substances and drugs with new mechanisms of action, was associated with an increase in the number of patients diagnosed thereafter. [ABSTRACT FROM AUTHOR]