Timely Spirometry is Associated with Lower All-Cause Mortality: a Nationwide Obstructive Cohort Study.

Abstract

Background: Despite spirometry is the gold standard to diagnose chronic obstructive pulmonary disease, it is underused in clinical practice.

Research question: Which factors are associated with timely spirometry (at chronic treatment initiation) in a clinically relevant population of people starting chronic treatment for respiratory symptoms? Is this diagnostic test associated with lower mortality risk?

Methods: Incident adult users of chronic respiratory medication were identified in Belgian nationwide data. The odds on timely spirometry were examined by multivariable logistic regression and impact on survival by multivariable Cox regression analysis. In those not receiving timely spirometry, factors related to further delay in spirometry were analyzed with multivariable Fine-Gray subdistribution hazard regression.

Results: Among 146,205 chronic treatment initiators, 20.9% had spirometry at treatment initiation, and 13.8% received spirometry during follow-up. While primary care physicians prescribed 81.1% of initiated treatments, general practitioners performed only 5.1% of all spirometry tests. People who received spirometry at treatment initiation had a 34% lower mortality risk (aHR: 0.66, 95%CI 0.63-0.70) and used less short-acting bronchodilators. Smoking, respiratory morbidities and congestive heart failure increased chance of spirometry. In contrast, female sex, age under sixty or over eighty, cognitive impairment and frailty lowered chance of spirometry both at initiation and during follow-up. Low socio-economic status, depression/anxiety, and antibiotic use were associated with a lower chance of spirometry at treatment initiation, while during follow-up, antibiotic use was associated with a higher chance of spirometry over time. Additionally, anemia and cachexia were associated with a lower chance during follow-up.

Interpretation: Only one in three initiators of chronic treatment for obstructive lung disease received spirometry. Spirometry was particularly underused in primary care. Especially (never-smoking) females and vulnerable patients may be at increased risk for underdiagnosis and suboptimal treatment. Importantly, spirometry at treatment initiation was significantly associated with better prognosis, possibly through better-tailored care.