The introduction of subsidised TNF inhibitor therapy has not changed all-cause hospital admission or ED visit rates for patients with ankylosing spondylitis (AS).
A WA study of 31,709 hospital admissions for AS between 1990 and 2015 found overall admission rates per 100,000 increased between 1990 and 2002, then declined to 2005 and remained relatively stable until a further decline in 2012.
Despite the introduction of subsidised TNFi in August 2004, the mean overall annual admission rate for AS patients post-2005 was not different from the pre-2005 period (RR: 0.95).
“The mean length of hospital stay decreased from 5.3 (± 9.3) days pre-2005 to 4.3 (± 9.9) days after 2005 (p < 0.01), while in-hospital mortality was similar in both periods (0.7 vs. 0.9%, p = 0.2),” the study said.
“Direct hospital-based health care costs were AU$14 million in both the pre- and post-2005 period, while the costs for TNFi drug and intravenous infusions added an average of AU$10 million to the costs.”
The study also showed that a decade of TNFi therapy did not have a major impact on admission rates for a broad range of complications and comorbidities including cardiovascular disease.
“This limited effect of TNFi on these crude outcomes may be due to the longer disease duration in this cohort of established AS patients and it would be of interest to see admission rate and type data for AS patients starting TNFi at an early age.”
“Interestingly, there was a significant decrease in injury-related admissions since 2005 and while tempting to relate this to the better physical functional status in AS patients on TNFi therapy, this remains speculative, especially as ED visit rates did not change over time.”
Infection rates in AS patients were low in both time periods (<2%) but increased after the introduction of TNFi therapy as did cancer rates.
The study, published in Rheumatology and Therapy, said whether or not the $ 10–15 million annual health care costs for AS patients in WA stacked up against improvements in quality of life, productivity, and non-hospital-based care remained unclear.
“Longitudinal and detailed study of AS-related resource use can provide crucial information for cost-effectiveness and improve our understanding of the natural disease history.”
Lead author Professor Johannes Nossent, from the University of WA and Sir Charles Gairdner Hospital, told the limbic that clinicians can’t tell their AS patients that using TNF inhibitors will keep them out of hospital.
“That doesn’t seem to be the case. It would suggest that for patients who started on TNF inhibitors after 5-10 years of disease …the risk factors for hospitalisation stay the same.”
He said the findings that TNF inhibitors didn’t reduce hospital admissions was not a big surprise however… “based on the fact that our cohort was on average 40+ years old when they entered the study, which means they had their disease for probably 15 years so it may have been ‘too little, too late’ to prevent disease complications which require admission.”
He said it would be interesting to do the same study in patients that start TNF inhibitors at a very early age.
“We had a similar look in rheumatoid arthritis…we see that admissions have decreased but that is largely at a time point where people started using methotrexate as a co-drug for RA. Following that decrease, we see a mild decrease in the number of admissions for patients once they start on biologics.”
Professor Nossent added that they didn’t have any data on pain levels, quality of life, work capacity etc – other outcomes that should be in the equation when evaluating the benefits of TNF inhibitors in AS patients.