Natural history of nonspecific pulmonary function tests

Iyer et al re-checked PFTs on 1,284 people with nonspecific results (low FEV1 or FVC but normal TLC and FEV1/FVC ratio), at a median of 3 years after the abnormal test. 64% continued to have the nonspecific result; 16% had restriction; 15% had obstruction; 2% had a mixed pattern; 3% were normal. They recommend changing the current guidelines that label these people as having obstruction. CHEST 2011;139:878-886.