[A preliminary study of the distribution and the characteristics of nonspecific pulmonary function]

To investigate the manifestations, pulmonary function test (PFT) characteristics and imaging features of patients with nonspecific pulmonary function (NSPF).

All the data from the same PFT apparatus in Beijing Hospital were collected from January 2003 to December 2012. NSPF was defined as normal FEV1/FVC and TLC, but decreased FEV1 or FVC or both. Patients with complete clinical data from January 2012 to June 2012 were enrolled into this analysis. The NSPF group was compared with the normal group, the obstructive group, the restrictive group and the mixed group.

There were totally 14 771 cases of PFT on this apparatus during 10 year period, and those with NSPF were 2759 (18.68%). From January 2012 to June 2012, 341 patients were enrolled into this study with a sex ratio of 1.37:1, and an average age of 66±12 years. Compared with the normal group, the NSPF group had a significantly higher rate of small airway abnormalities and elevated RV/TLC. Multiple logistic regression analysis showed that statistical differences were found in TLC%pred (OR=0.668, P<0.01, 95%CI 0.563-0.791), FEF25-75%pred (OR=0.963, P<0.01, 95%CI 0.939-0.988), RV%pred (OR=1.144, P<0.01, 95%CI 1.075-1.217), and RV/TLC (OR=1.31, P<0.01, 95%CI 1.15-1.492). Compared with the obstructive group, the NSPF group had a significantly lower rate of small airway abnormalities. Multiple logistic regression analysis showed that female gender(OR=15.283, P<0.001, 95%CI 3.526-66.248), TLC%pred (OR=0.961, P=0.02, 95%CI 0.928-0.994), and FEF50%%pred (OR=1.189, P<0.001, 95%CI 1.103-1.281) were significantly different between the 2 groups. Respiratory symptoms were more common in the NSPF group. Airway diseases were diagnosed in more cases of the NSPF group when compared to the normal group, but in fewer cases when compared to the obstructive group. Clinical manifestations and imaging features of the NSPF cases were not specific.

NSPF is a common clinical condition which mainly affects the small airway function with some degree of restrictive dysfunction. NSPF has limited predictive value for diagnosis because the manifestations and imaging features are not specific.