D3.134 - Pulmonary rehabilitation at altitude: Is there an optimal season?

Asthma is a common chronic, inflammatory disease of the airways, which can be worsened by environmental triggers. Effective asthma management includes minimizing exposure to environmental triggers, which differ in type and magnitude in different environments and seasons. Seasonal variation influences asthma control, but it remains unclear whether the outcomes of Alpine Altitude Climate Treatment (AACT) are also affected by season. This retrospective cohort study therefore aims to assess if there are seasonal differences in AACT outcomes. 

Data from 1359 admissions to a specialized asthma rehabilitation center between 2008 and 2024 were used. Admissions were categorized into three periods (warm, cold and mixed) and five seasons (winter, spring, summer, fall and mixed season).  Associations between period or season and Post-rehabilitation outcomes (Asthma Control Questionnaire (ACQ), Asthma related Quality of Life Questionnaire (AQLQ) and the 22 item Sinonasal Outcome Test (SNOT-22)) were assessed using ANCOVA models, adjusting for baseline scores, sex, age, admission duration, and history of multiple admissions.  

No overall seasonal or periodic effects were found for asthma control, quality of life or sinonasal outcomes. Baseline scores were the most important predictor of post-rehabilitation outcomes in all analyses. A significant, but not clinically relevant, effect of cold period was found on sinonasal complaints (SNOT score mean(95%CI) cold 28.92(27.41-30.43) vs warm period 32.90(31.35-34.44)p<.001). We observed sex differences, where women showed worse asthma control in the cold period (ACQ mean(95%CI) women: 1.81(1.70-1.92), men: 1.32(1.15-1.48), p<.001) and worse quality of life in winter (AQLQ mean(95%CI) women: 5.40(5.21-5.60), men: 5.87(5.59-6.14), p=.004). Additionally, atopic patients showed significantly better asthma control (ACQ mean(95%CI) scores 1.25(1.06-1.44) vs 1.78(1.50-2.06), p=.002) and asthma related quality of life (AQLQ mean(95%CI) 5.80(5.61-5.99) vs 5.27(5.01-5.52), p<.001) during spring, compared to the non-atopic patients. 

There is no optimal season for pulmonary rehabilitation in the alpine climate (AACT). For women the warm period showed slightly better outcomes and for atopic patients spring might be the best time for AACT. However, pre-rehabilitation scores are the most important predictor for all outcomes, and therefore timely referral may be more important than seasonal preferences.