Accuracy of Spirometry in Diagnosing Pulmonary Restriction in Elderly People

OBJECTIVES: To compare the accuracy of a diagnosis ofpulmonary restriction made using forced vital capacity(FVC) less than the lower limit of normal (LLN) with thecriterion standard diagnosis made using total lung capacity(TLC) less than the LLN in an elderly population.DESIGN: Retrospective analysis.SETTING: A teaching hospital.PARTICIPANTS: Five hundred sixty-four ambulatory andacute care hospital patients aged 65 to 96 underwent com-plete pulmonary function evaluation.MEASUREMENTS: Sensitivity, specificity, positive andnegative predictive values (PPV, NPV) of diagnosis of pul-monary restriction defined as FVC less than the LLN werecalculated in the overall sample and after stratificationaccordingtobronchialobstruction.ExpectedPPVandNPVat different background prevalence of true pulmonaryrestriction (5% and 15%) were calculated using the Bayestheorem.RESULTS: Low sensitivity (0.32) and high specificity(0.95) were found, with an area under the receiver operat-ing characteristic curve (AUC) of 0.89. In participantswithout bronchial obstruction, specificity was even higher,although sensitivity decreased to 0.28 (AUC50.92). ThePPV was good (0.81), whereas with a low to moderate apriori probability (prevalence from 5% to 15%) the NPVwas fair ( 0.89).CONCLUSION: A reduction in FVC below LLN cannotreliably identify true pulmonary restriction in elderly peo-ple, confirming previous findings in the adult population.Normal FVC, instead, can effectively exclude pulmonaryrestriction regardless of the presence of bronchial obstruc-tionwhentheaprioriprobabilityislowormoderatelyhigh.J Am Geriatr Soc 57:2107–2111, 2009.Key words: lung restriction; elderly; pulmonary functiontest; diagnostic accuracy