Six studies met the inclusion criteria (n=1,861 patients; range 161 to 703). All six studies clearly described their selection criteria, used an adequate reference standard, avoided verification and incorporation bias, and reported reasons for withdrawals. Four studies clearly recruited a representative sample, four blinded investigators when interpreting results, but only one reported uninterpretable/intermediate results.
Patient history: Eight patient history tests demonstrated independent diagnostic value for chronic obstructive pulmonary disease (COPD): over 45 years of age (one study), female (one study), difficulty breathing (two studies), wheezing (two studies), smoking (two studies) , previous consultation for cough or wheezing (one study), self-report history of COPD (one study), and allergy symptoms (one study). Family history of asthma was not of independent diagnostic value.
Physical examination: Five physical examination tests demonstrated independent diagnostic value for COPD: wheezing, forced expiratory time nine seconds and six seconds, maximum laryngeal height and prolonged expiration, all in single studies. Reduced breath sounds, rales/rhonchi, laryngeal descent, Hoover sign and clinical impression were not of independent diagnostic value.