Self-monitoring symptoms and pulse oximetry to predict imminent altitude illness in patients with chronic obstructive pulmonary disease.

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) are susceptible to altitude-related adverse health effects (ARAHE).

RESEARCH QUESTION: Does structured self-monitoring (SSM) predict imminent ARAHE in COPD patients during altitude travel.

METHODS

Patients with moderate to severe COPD without chronic respiratory failure, living below 800 m, ascended by bus within 5 h to a clinic at 3100 m and stayed there for 2 days. During the altitude sojourn, patients regularly monitored themselves for symptoms of acute mountain sickness (AMS) and/or drops of pulse oximetry (SpO2) to ≤84%, events designated as positive SSM. Measures of diagnostic accuracy of SSM in predicting subsequent ARAHE (defined as AMS Lake Louise score >4 and/or SpO2 <80% for >30 min or <75% for >15 min and/or any condition requiring medical intervention) were computed. www.ClinicalTrials.org NCT03957759.

RESULTS

Among 153 COPD patients (79 women, mean ± SD age 57 ± 10y) travelling to 3100 m, SSM was positive in 55 (36%), ARAHE occurred in 116 (76%). Concordance statistics indicated a diagnostic accuracy of SSM in predicting ARAHE of 0.65 (95%CI 0.58 to 0.72). In SSM positive patients, the odds ratio for ARAHE was 4.9 (95%CI 1.8 to 12.9). Positive and negative predictive values of SSM for ARAHE were 91% (95%CI 80 to 97) and 33% (95%CI 24 to 43). In exploratory analyses, supplementing SSM by nocturnal pulse oximetry with alarm capability enhanced diagnostic accuracy considerably (sensitivity improved from 43% to 73% concordance statistic increased to 0.80).

CONCLUSIONS

Lowlanders with COPD ascending to 3100 m commonly experience ARAHE. Due to its high positive predictive value, performing SSM may allow patients to predict imminent ARAHE and take timely appropriate actions such as descend or use oxygen. Negative SSM does not reliably indicate a low risk of ARAHE.