Diffuse idiopathic skeletal hyperostosis is associated with reduced lung function independent of structural lung abnormalities

Diffuse idiopathic skeletal hyperostosis (DISH) has been associated with lower lung volumes and function, but it is unknown whether this is due to structural lung disease. This study aimed to investigate DISH and reduced lung function and volume in relation to structural lung disease in individuals with long-term smoking history.

Participants were included from the NELSON lung cancer screening trial. Structural lung abnormalities were automatically quantified (emphysema, airway wall thickness, and air trapping), or visually assessed (interstitial lung abnormalities, bronchiectasis, centrolobular emphysema) by two chest radiologists. Multivariate linear regression analyses were performed with adjustment for participant factors and structural lung disease.

Among 3514 subjects (100% male, mean age 60.4 years), DISH was present in 241 (6.7%). Individuals with DISH had lower prevalence of Respiratory Bronchiolitis Interstitial Lung Disease (5%vs. 10.4%, p = 0.04) and of centrilobular emphysema (3.3%vs. 7.6%, p = 0.009), but greater airway wall thickness (2.6 vs. 2.4 mm, p < 0.001). In multivariate linear regression analyses, DISH subjects had a 4.4% lower FEV₁ (95%CI: -7.1% to -1.7%), 150 ml lower FEV₁ (95%CI: -160, -140 ml), 4.0% lower predicted FVC (95%CI: -6.2%, -1.7%), 170 ml lower FVC (95%CI: -280, -70 ml) and 210 ml lower CT measured lung volume (95%CI: -40, -1 ml), compared to subjects without DISH.

In long-term smokers, DISH was associated with lower lung function and volumes, not explained by structural lung abnormalities on CT. These findings suggest that DISH may be an extrinsic factor contributing to reduced lung function as a result of thoracic cage stiffening.