Validation of a new clinical scoring system for acute bronchitis.

INTRODUCTION Although several clinical prediction rules exist for lower respiratory tract infection (LRTI), few are for acute bronchitis (acute bronchitis) and most have not been validated in high human immunodeficiency virus (HIV) prevalence settings. METHODS An Acute Bronchitis Severity Score (ABSS) was developed and validated during a randomized trial of antibiotic treatment for acute bronchitis. Ambulatory adults with productive cough of < or =2 weeks at out-patient respiratory disease clinics in Nairobi, Kenya, were recruited and assessed for clinical response to therapy. The ABSS quantitative ratings of LRTI-associated symptoms, physical signs and sputum Gram stain purulence were assessed using standard psychometric tests. RESULTS The ABSS was evaluated among 649 cases of acute bronchitis; 129 (20%) were HIV-seropositive. The ABSS had small floor and ceiling effects (1.8/0.2) and demonstrated high internal consistency (alpha-coefficient of 0.66) and internal validity, with a mean inter item total correlation of > or =0.25. Effect sizes from baseline to subsequent follow-up visits were large (>0.5). Wheezing and chest pain were associated with higher ABSS values, whereas irrelevant clinical variables were not. CONCLUSION The ABSS demonstrated good responsiveness, high internal consistency, good correlation with common respiratory signs and symptoms and high discriminatory validity among patients with acute bronchitis in a high HIV-seroprevalence setting.