Indications for Spirometry in Outpatients with Respiratory Disease*

Abstract

It has been suggested that spirometry should be incorporated into the routine examination of every patient, analogous to obtaining vital signs. To determine the impact of spirometry on the management of outpatients with respiratory disease, spirometry was performed on 150 consecutive patients (123 men and 27 women, mean age 57 +/- 12 years) seen in our pulmonary disease outpatient clinics. Patients with obstructive (n = 75), restrictive (n = 31), mixed (n = 26) or other respiratory diseases (n = 18) were initially assessed by history and physical examination and classified as improved, stable, or worse compared to previous visits. A clinical management plan (CMP) was formulated based on this initial evaluation. Spirometric results were then made available to the examiner who could then make changes in the proposed CMP. The addition of spirometric results caused alteration of the CMP in only eight (5 percent) patients; in the remaining 142 patients, results did not affect the CMP. Two clinical findings identified those patients whose CMP was most likely to be altered by spirometry: severity of lung dysfunction (determined from previous spirometry) and deterioration of clinical status (judged by history and physical examination). Of the eight patients whose CMP was changed after review of spirometry, six (75 percent) had previous severe ventilatory dysfunction (FEV1 or FVC less than or equal to 40 percent of predicted or FEV1/FVC ratio less than or equal to 0.40). In 6 of 38 patients (16 percent) with severe ventilatory dysfunction, CMP was altered after spirometry while only 2 of 112 patients (1.8 percent) with mild or moderate dysfunction had changes in their CMP. Patients who were clinically assessed as worse compared to their previous visit were more likely to have their CMP altered after review of spirometry when compared to those considered improved or stable by a ratio of 6:1. These results suggest that spirometry is most likely to supplement the physician's history and physical examination in the management of outpatients with pulmonary disease when the initial evaluation suggests that the patient has clinically deteriorated since the previous clinic visit, or when he or she has previous severe ventilatory dysfunction.