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2005

2005 A prospective study on patients admitted with acute exacerbation of chronic obstructive pulmonary disease: clinical features, infectious aetiology and short term outcome

Dr. Joan PC Fok, Department of Medicine and Therapeutics, Prince of Wales Hospital

Introduction
Chronic obstructive pulmonary disease (COPD) is now estimated to be the fourth leading cause of death in Hong Kong. Patients with acute exacerbations of COPD (AECOPD) account for 3% of all hospital admissions. Not only does AECOPD cause significant decline in lung function, it also has the potential to jeopardize the quality of life of patients. The aim of this study was to assess the infectious aetiology, clinical features and short term outcome of patients admitted to hospital with AECOPD in Hong Kong.

Methods
This is a single-centre prospective study conducted at a tertiary teaching hospital in the Eastern New Territories region of Hong Kong. Patients admitted to the hospital with AECOPD from May to October 2004 were recruited. The symptoms, demographic data, co- morbidities, results of blood tests, sputum cultures, rapid tests and viral isolations on nasopharyngeal aspirates (NPA), antibiotic treatment and the length of hospital stay were noted. All recruited patients were subsequently reassessed in one month after their admissions with spirometry, weight and height measurements. All patients were then prospectively followed for a period of up to three months post admission. Clinical outcome such as readmissions and death was recorded.

Results
Altogether 178 patients were recruited and this corresponded to 257 episodes of AECOPD. The mean age (SD) of the patients was 76.3 (7.6) years. The mean FEV1 (SD) was 42.9 % (17.6) of the predicted values and the duration of hospital stay was 14.6 (14.8) days (median 11 days). Out of 257 episodes of AECOPD, of which one routine sputum culture was requested in each admission, 206 sputum samples were sent for routine bacterial culture within 48 hours after admission, and 53 (25.7%) had positive growth. Pseudomonas aeruginosa (6.8%), Haemophilus influenzae (6.3%) and Streptococcus pneumoniae (4.9%) were the commonest bacteria found in sputum cultures. 205 sputum samples were sent for mycobacterium culture and positive growth of mycobacteria was found in 6 (2.9%) whereas Mycobacterium tuberculosis was isolated in 3 sputum samples. In addition, 213 NPAs were sent for viral screening. 23 (10.8%) were subsequently found to be positive on viral culture. Influenza A was the commonest virus found with a prevalence of 7.5%.

The mean and median lengths of stay of patients admitted with AECOPD were 14.6 (14.8) and 11 days respectively. The use of LTOT and NIPPV during admission were associated with a prolonged length of stay. 1 (0.4 %) episode of AECOPD required intubation whereas 41 (16 % of all episodes of AECOPD) received NIPPV. 57 (32%) patients were readmitted in 3 months. Patients on LTOT and those who were on inhaled corticosteroid were more likely to be readmitted. 17 (9.6%) patients died within 3 months after the index admission.

Conclusion
In this group of elderly patients who were admitted with AECOPD between May and October 2004, 25.7% of the sputum cultures yielded positive growth of bacterial organisms, whereas 10.8% of the NPAs were positive for viral pathogens. These results suggest that bacterial and viral infections are important causes of AECOPD in our locality.

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