Prevalence and incidence of Chlamydia pneumoniae antibodies among the healthy elderly and patients with chronic obstructive pulmonary diseases.

Chlamydia pneumoniae is an obligatory intracellular bacteria which can cause both acute and chronic respiratory tract infection. The significance of chronic and recurrent respiratory infection may be of prime importance in chronic obstructive pulmonary diseases (COPD). The purpose of this study was to determine the prevalence and incidence of C. pneumoniae antibodies in elderly COPD patients compared to a healthy elderly control group. C. pneumoniae antibodies were detected by an enzyme-linked immunosorbent assay in serum samples obtained from 127 elderly COPD patients and a 131 healthy elderly control group. The results showed that the seroprevalence of C. pneumoniae infection as determined by the existence of specific IgG or IgA or IgM antibodies was 96.1% in the COPD patients and 75.6% in the control group (p < 0.01). The prevalence of individual C. pneumoniae IgG, IgA and IgM in elderly COPD vs healthy control was 85.8% vs 66.4%, 85.0% vs 51.1% and 3.9% vs 0%, respectively. The incidence or seroconversion rate of C. pneumoniae antibodies after one year follow-up was found to be 33% in the COPD patients and 67.9% in the control group. High prevalence and incidence of C. pneumoniae antibodies indicates that both acute and chronic C. pneumoniae infection play a role in elderly COPD patients. Therefore, antibiotics of choice for C. pneumoniae infection should probably be considered.

Economic evaluation of influenza vaccination in Thai chronic obstructive pulmonary disease patients.

To determine the cost-effectiveness and cost-benefit of influenza vaccination in chronic obstructive pulmonary disease (COPD) patients the authors conducted a stratified randomized, double-blind, placebo-controlled trial from June 1997 to November 1998 at a university hospital in Thailand. A total of 125 COPD patients were stratified based on their FEV1 as mild COPD (FEV1 > or = 70% predicted), moderate COPD (FEV1 50-69% predicted) and severe COPD (FEV1 < 50% predicted) and in each severity stratum they were randomized to the vaccine group (received intramuscular injection with purified trivalent split-virus vaccine containing A/Texas/36/91 (H1N1), A/Nanchang 1933/95 (H3N2) and B/Harbin 107/94) or the placebo group (received intramuscular injection with vit B1). Number of episodes of acute respiratory illness (ARI) related to influenza (clinical ARI + a serum hemagglutination inhibition antibody titre of 38 or greater and a four fold titre increase in convalescent serum compared to acute serum) as well as severity of each ARI (outpatient treatment, hospitalization or required mechanical ventilation) and costs of treatment (direct medical costs comprised real drug costs from the hospital dispensary in outpatient cases and real charges in hospitalization cases) were collected and analyzed for the cost-effectiveness and cost-benefit of influenza vaccination. The incidence of influenza-related ARI in the study year was 27 per cent in the placebo group and 6.4 per cent in the vaccine group (relative risk [RR] 0.24, vaccine effectiveness 76%). The incidence was 27.3 per cent, 23.5 per cent and 29.2 per cent in mild, moderate and severe COPD respectively in the placebo group and 4.3 per cent, 12.5 per cent, and 4.3 per cent in the mild, moderate and severe COPD respectively in the vaccine group (RR 0.16, 0.53 and 0.15; vaccine effectiveness 84%, 47%, and 85% respectively). The incremental cost-effectiveness ratios demonstrated that for every 100 patients with mild COPD whom the authors decided to vaccinate, the cost would be 24,840 baht more and would prevent 18.2 outpatients, 4.8 hospitalizations and 0 patient from mechanical ventilation due to ARI related to influenza. Likewise, the authors would have prevented 5.1 outpatients, 5.9 hospitalizations, 5.9 mechanical ventilation and 20.8 outpatients, 3.9 hospitalizations, 8.3 mechanical ventilation for every 100 moderate COPD and every 100 severe COPD patients vaccinated respectively. More than 90 per cent of the costs of treatment of influenza-related ARI were costs of hospitalization and for patients with moderate and severe airflow obstruction, more than 90 per cent of these costs were attributed to the costs of treating the patients who required mechanical ventilation. Predicted cost savings for every 100 mild COPD, 100 moderate COPD and 100 severe COPD patients vaccinated were 125,629 baht, 538,184.3 baht, and 680,647.1 baht respectively. In conclusion: Influenza vaccination is highly effective in the prevention of acute respiratory illness related to influenza virus infection in COPD, regardless of severity of airflow obstruction. Vaccination is more cost-effective in preventing mechanical ventilation episodes and more cost-benefit in patients with more severe airflow obstruction. Influenza vaccination should be recommended to all patients with COPD with the higher priority provided to patients with more severe airflow obstruction.

The prevalence and incidence of COPD among urban older persons of Bangkok Metropolis.

COPD substantially affects the national healthcare resource and healthcare cost especially among the older persons. Identifying the accurate prevalence and incidence reflects the scale of problem posed by COPD. This epidemiological study using the criteria for diagnosing COPD based on ratio of FEV1.0/FVC less than 70 per cent and the reversibility of less than 15 per cent increase of post bronchodilator FEV1.0 in the absence of parenchymal lesions and cardiomegaly in CXR (PA and lateral view) revealed the prevalence (1998) of COPD among the 3094 older persons aged 60 years and over in the communities of Bangkok Metropolis 10 km around Siriraj Hospital was 7.11 per cent (95% CI: 6.21-8.01), whereas the incidence (1999) of COPD was 3.63 per cent (95% CI: 2.83-4.43). Both the prevalence and the incidence were increased with increasing age.The disease occurred predominantly among male smokers. The distribution of mild : moderate : severe COPD in the prevalence study was 5.6:2.2:1. The current findings also suggest that tobacco smoking is the prime important cause of COPD and the indoor pollution especially cooking smoke is not significant. In particular, the unexpectedly high incidence compared with prevalence in this population probably represents the warning message to the national policy maker for prompt and effective health promotion and disease prevention to prevent further social and economic loss.