medwireNews: Over half of the incremental healthcare costs associated with severe asthma relative to mild or no asthma can be attributed to comorbid conditions, indicate Canadian study findings.
Of 16 major disease categories assessed, respiratory diseases other than asthma were the most prominent comorbid condition identified.
“Our findings provide direct evidence to support the importance of considering comorbidity costs to the cost-effectiveness evaluation of interventions for severe asthma,” say Wenjia Chen (University of British Columbia, Vancouver, Canada) and co-researchers in Thorax.
They add: “Beyond health economics, these findings suggest the importance of taking a holistic approach towards managing patients with severe asthma.”
Using health administrative data in British Columbia, from 1996 to 2016, the team identified 6402 patients with severe asthma who were matched to the same number with non-severe asthma and no asthma.
Individuals with severe asthma incurred annual healthcare costs that were approximately three times higher than those for individuals without asthma, at CAD$ 4125 versus $ 1345 (US$ 3093.75 vs $ 1008.75; € 2805.00 vs € 914.60). This corresponded to an incremental cost of $ 2779 per person–year (US$ 2084.25; € 1889.72), the team reports.
Asthma-specific costs explained just 29% of the increment, they note, whereas 54% was attributed to comorbidities, primarily respiratory conditions other than asthma, mental or behavioral disorders, and diseases of the nervous and digestive systems, which were more frequent in patients with than without asthma. The final 16% could not be attributed to any specific disease.
The pattern was similar when comparisons were made with non-severe asthma patients, with costs twofold higher for those with severe asthma, at $ 4125 versus $ 2202 (US$ 3093.75 vs $ 1651.50; € 2805.00 vs € 1497.36), giving an incremental cost of $ 1922 per person–year (US$ 1441.50; € 1306.96). Of this, 35% was attributable to asthma and 52% to comorbidities, with the remaining 13% unattributable.
The comorbidities contributing to the higher costs were mainly respiratory conditions other than asthma and diseases of the nervous and digestive systems, but as the conditions were only slightly more prevalent in severe compared with non-severe asthma patients, the team suggests that it is the severity rather than the frequency having the greatest effect. Costs associated with mental and behavioral disorders did not differ significantly between those with severe and non-severe asthma.
Chen and colleagues point out that the “most costly comorbidities in asthma are predominantly driven by a subset of patients with severe asthma, whereas non-severe patients do not significantly differ from the general population on the costs of such comorbidities.”
The three largest components in the incremental costs for severe asthma were hospitalizations for comorbidities, which accounted for a third, followed by medications for asthma and medications for comorbidities.
The researchers conclude that the study “highlights the importance of considering the burden of multimorbidity in evidence-informed decision making for patients with severe asthma.”
By Lucy Piper
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