Underdiagnosis of Obstructive Lung Disease

Findings From the French CONSTANCES Cohort

Marie-Christine Delmas; Laetitia Bénézet; Céline Ribet; Yuriko Iwatsubo; Marie Zins; Rachel Nadif; Nicolas Roche; Bénédicte Leynaert

Disclosures

BMC Pulm Med. 2021;21(319) 

In This Article

Results

Study Population and Previous Diagnoses of OLD

Spirometry results were available (≥ 3 acceptable and ≥ 2 reproducible manoeuvres) for 19,398 out of 34,238 CONSTANCES participants included in 2013 or 2014 (Figure 1). Overall, 765 participants had FEV1/FVC ratio less than LLN, leading to a weighted prevalence of airflow limitation of 4.6% [95% confidence interval: 4.1–5.1%]: 5.2% [4.5–6.0%] in men and 4.0% [3.3–4.6%] in women (P = 0.01). Using FEV1/FVC ratio < 0.70, the prevalence of airflow limitation was 5.0% [4.5–5.5%]: 6.6% [5.8–7.4%] in men and 3.5% [2.9–4.1%] in women (P < 0.001).

In the following analyses, we considered only participants with airflow limitation (FEV1/FVC < LLN). Their characteristics are described in Table 1. Women with airflow limitation were younger, were more likely to be never-smokers, and had a better lung function than men. Men with airflow limitation were more likely to report a previous diagnosis of COPD and cardiovascular comorbidities. Overall, a previous diagnosis of OLD (asthma, COPD, emphysema, chronic bronchitis, or bronchiectasis) was reported by 35.6% of individuals with airflow limitation, leading to a proportion of undiagnosed OLD of 64.4%. This proportion did not differ in men and women.

Characteristics of Individuals With Airflow Limitation, With Versus Without a Previous Diagnosis of OLD

We investigated the characteristics of individuals who reported a previous diagnosis of asthma or COPD as compared to those with undiagnosed OLD (Table 2). Individuals with undiagnosed OLD had sociodemographic characteristics and smoking habits that ranged between those of individuals with diagnosed asthma and those with diagnosed COPD, although they tended to be closer to those with diagnosed asthma. However, they reported fewer symptoms and had better lung function. Overall, 60.3% of individuals with undiagnosed OLD reported no respiratory symptoms, compared to 27.4% and 20.3% of those with diagnosed asthma and COPD, respectively.

Symptoms by Severity of Airflow Limitation and Previous Diagnoses

To investigate whether under-diagnosis might relate to different patterns of symptoms, we explored the relationship between respiratory symptoms and airflow limitation severity, stratified by a previous diagnosis of OLD (Table 3). Among individuals with undiagnosed OLD, the prevalence of respiratory symptoms increased markedly with the severity of airflow limitation (from 28.8% in individuals with mild airflow limitation to 84.1% in those with severe airflow limitation). Among individuals with diagnosed OLD, the proportion of those reporting symptoms was already high (71.2%) in those with mild airflow limitation and increased up to 80.9% in those with severe airflow limitation. Conversely, considering individuals with respiratory symptoms, 49.4% had undiagnosed OLD: 60.8% in those with mild airflow limitation, and 44.9% in those with moderate to severe airflow limitation.

Factors Associated With Undiagnosed OLD

After adjusting for gender, age, education level, tobacco consumption, respiratory symptoms, and cardiovascular history, only two factors were found to be independently associated with undiagnosed OLD: ever-smokers with a tobacco consumption of ≥ 10 pack-years and individuals without respiratory symptoms had a higher risk of undiagnosed OLD (Table 4, model 1). These associations remained unchanged after further adjustment for FEV1% predicted (model 2), and preserved lung function was also independently associated with a higher risk of undiagnosed OLD. Restricting the study population to participants with moderate to severe airflow limitation (FEV1 < 80% predicted) or those aged 40 years and over gave similar results (Additional file 1: Tables A.1 and A.2). When restricting the study population to participants under 40 years, however, only the absence of respiratory symptoms was associated with an increased risk of undiagnosed OLD (Additional file 1: Table A.3).

processing....