The temporal association between hospital admissions, biological therapy usage and direct health care costs in rheumatoid arthritis patients.

The Australian Pharmaceutical Benefits Scheme (PBS) has subsidised biological therapy since 2003. We investigated the association between biological therapy for RA hospitalisation rates and health-care costs.Hospital admissions for RA patients between 1995 and 2014 were identified in the Western Australia (WA) Hospital Morbidity Data Collection (ICD codes 714 and M05.00-M06.99). State-specific dispensing data for conventional and biological therapies for RA was obtained from Statistics Australia and expressed as defined daily doses/1000 population/day (DDD) using WA population census. Principal component analysis (PCA) was applied to determine the relationship between DMARDs use and hospital admission rates.A total of 17,125 patients had 50,353 admissions with a diagnostic code for RA. Between 1995 and 2002, the number of RA admissions fell from 7.9 to 2.6/1000 admissions, while conventional therapy use rose from 1.45 to 1.84 DDD. Between 2003 and 2014, RA admissions decreased further to 1.9/1000 hospital admissions, while conventional therapy use increased to 2.19 DDD and biological therapy from 0.01 to 1.0 DDD. In PCA, conventional and biological therapies use had an inverse relationship with hospital admission rates. Annual costs of biological therapy utilisation was 22.5 million in 2003-2014, while the annual cost saving of RA hospital admissions was 9.2 million.The increased use of conventional therapy use for RA has coincided with a significant decline in hospital admissions for RA patients in WA, while a more modest further decline followed biological therapy introduction. Biological therapy was not as cost-effective as conventional in relation to RA hospital admissions costs.