Make the Diagnosis: Airflow Limitation
A systematic review identified 32 sources of information from studies done worldwide on the prevalence of obstructive airways disease.13 Nine of the 32 studies used a spirometric reference standard, similar to what is advocated for clinical practice; 8 of these had data that allowed us to compare the overall prevalence and sex-specific prevalence. The summary overall prevalence was 7.1% (95% CI, 5.2%-9.3%). Men (11%; 95% CI, 8.5%-14%) had about twice the rate as women (6%; 95% CI, 3%-10%) (see Table 13-7).
Table 13-7Prior Probability of Obstructive Airways Disease Differs by Sex
Population for Whom Obstructive Airways Disease Should Be Considered
All adults, especially those who smoke and are aged 45 years or older.
Detecting the Likelihood of Obstructive Airways Disease
Table 13-8Likelihood Ratios for Best Single Findings and for Multivariate Models |Favorite Table|Download (.pdf) Table 13-8 Likelihood Ratios for Best Single Findings and for Multivariate Models
|Single Best Findings That Are the Easiest to Measure ||Likelihood Ratio |
|Smoking status, > 40 pack-years ||12 |
|Auscultated wheezing or laryngeal height ≤ 4 cm ||≍4 |
|To “Rule In” Obstructive Disease, Must Use a Multivariate Modela ||Posterior Odds of Disease, Probability (%) |
|Smoking > 55 y and wheezing symptoms and auscultated wheezing ||156 (99) |
|History of OAD and smoking > 40 pack-years and age ≥ 45 y and laryngeal height ≤ 4 cm ||220 (99) |
|To “Rule Out” Obstructive Disease, Must Use a Multivariate Modela ||Posterior Odds of Disease, Probability (%) |
|Smoking < 30 y and no wheezing symptoms and no auscultated wheezing ||0.02 (1.5) |
|No history of OAD and smoking < 40 pack-years and age < 45="" y="" and="" laryngeal="" height=""> 4 cm ||0.03 (3) |
Spirometry using the pulmonary laboratories definition for the presence of obstructive airways disease.
Original Article: Does the Clinical Examination Predict Airflow Limitation?
Clinical Scenarios—Do These Patients Have Airflow Limitation?
In each of the following cases, the clinician needs to decide whether the patient has airflow limitation. In case 1, a 63-year-old man who has smoked 2 packs of cigarettes per day for the past 47 years presents with decreased exercise tolerance caused by shortness of breath. In case 2, a 35-year-old woman complains of coughing, wheezing, and shortness of breath every autumn. In case 3, an 18-year-old man is brought to an emergency department, with extreme difficulty breathing that began earlier that evening.
Why Is It Important to Detect Airflow Limitation by Clinical Examination?