Estimación de la variabilidad inicial interobservador de la espirometría forzada en el estudio epidemiológico multicéntrico IBERPOC

[Costs of chronic obstructive pulmonary disease in Spain. Estimation from a population-based study]

OBJECTIVE

In the studies carried out to date, the cost of chronic obstructive pulmonary disease (COPD) may have been overestimated due to the inclusion of previously diagnosed patients seeking medical attention for their symptoms. As a result, the severity of the cases included in these studies may have been greater than in an unselected sample of the general population. The aim of the present study was to estimate the direct cost of COPD on the basis of a representative sample of the overall Spanish population between 40 and 69 years of age (from the IBERPOC study).

METHOD

The cost was evaluated retrospectively by means of a questionnaire completed by the 363 patients with COPD from the IBERPOC study with questions referring to the previous year. Standardized spirometry was performed on all the patients by a pneumologist in each of the 7 geographical areas in which the study was carried out.

RESULTS

Hospitalization accounted for the greatest expenditure (41% of total), followed by drug therapy (37%). The cost was euro;98.39 per patient, and euro;909.50 per previously diagnosed patient. The cost per person of severe COPD was more than 3 times that of moderate COPD and more than 7 times that of mild COPD. The estimated annual cost of COPD in Spain was euro;238.82 million (for 1997).

CONCLUSION

The present study, which was the first to estimate the cost of COPD in a representative sample of the general population, found the cost to be lower than in studies analyzing samples of patients with previous diagnoses of COPD. The cost distribution is not in line with recommended health care practices, underlining the need to optimize resources used to monitor and treat the disease, with an emphasis on early diagnosis.

[Spirometry: quality in the respiratory medicine clinics of a public health care area]

BACKGROUND

Spirometry can be considered a routine way to evaluate patients with respiratory complaints, both inside and outside the hospital setting.

OBJECTIVE

To assess the quality of spirometry in a public health care area with respect to two factors: the technicians' performance and the calibration of spirometers.

MATERIAL AND METHOD

Four health care clinics were studied. Four technicians participated and the four spirometers were tested at different volumes (calibration syringes 1L and 3L) and different flows (explosive decompression). Eight patients with COPD participated in the study of inter-technician variability.

RESULTS

Agreement among the technicians was very high: 0.98-0.99 for FEV1 and 0.91-0.98 for FVC. The mean results obtained by the technicians were: FEV1 = 2.15 0.03, range 2.20-2.14; FVC = 3.25 0.05, range 3.30-3.21 (ns). Volumetric readings from the spirometers were correct for the 1I calibration syringe, but 2 out of 4 spirometers lost linearity with the 3I calibration syringe. One spirometer gave readings out of range for all flow levels, and 2 out of 4 spirometers were out of range at low flows.

CONCLUSIONS

1. Results obtained by different technicians were not significantly different and there was high agreement among them, confirming that performance of spirometry was good. 2. The spirometers showed poor linearity at low flows.

Smoking characteristics: differences in attitudes and dependence between healthy smokers and smokers with COPD

OBJECTIVE

To ascertain the differences in smoking characteristics between a group of smokers with COPD and another group of healthy smokers, both of which were identified in a population-based epidemiologic study.

DESIGN AND PARTICIPANTS

This is an epidemiologic, multicenter, population-based study conducted in seven areas of SPAIN: A total of 4,035 individuals, men and women aged 40 to 69 years, who were selected randomly from a target population of 236,412 subjects, participated in the study.

INTERVENTIONS

Eligible subjects answered the European Commission for Steel and Coal questionnaire. Spirometry was performed followed by a bronchodilator test when bronchial obstruction was present. The Fagerström questionnaire was used for study of the degree of physical nicotine dependence, and the Prochazka model was followed for analysis of the smoking cessation phase.

RESULTS

Of 1,023 active smokers, 153 (15%) met the criteria for COPD. Smokers with COPD were more frequently men (odds ratio [OR], 2.18; 95% confidence interval [CI], 1.21 to 3.95), were > or = 46 years of age (OR, 1.97; 95% CI, 1.18 to 3.31), had a lower educational level (OR, 1.96; 95% CI, 1.23 to 3.14), and had smoked > 30 pack-years (OR, 3.70; 95% CI, 2.42 to 5.65). Smokers with COPD showed a higher dependence on nicotine than healthy smokers (mean [+/- SD] Fagerström test score, 4.77 +/- 2.45 vs 3.15 +/- 2.38, respectively; p < 0.001) and higher concentrations of CO in exhaled air (mean concentration, 19.7 +/- 16.3 vs 15.4 +/- 12.1 ppm, respectively; p < 0.0001). Thirty-four percent of smokers with COPD and 38.5% of smokers without COPD had never tried to stop smoking.

CONCLUSIONS

Smokers with COPD have higher tobacco consumption, higher dependence on nicotine, and higher concentrations of CO in exhaled air, suggesting a different pattern of cigarette smoking. Cases of COPD among smokers predominate in men and in individuals with lower educational levels. A significant proportion of smokers have never tried to stop smoking; thus, advice on cessation should be reinforced in both groups of smokers.

Geographic variations in prevalence and underdiagnosis of COPD: results of the IBERPOC multicentre epidemiological study

OBJECTIVES

To ascertain the prevalence, diagnostic level, and treatment of COPD in Spain through a multicenter study comprising seven different geographic areas.

DESIGN AND PARTICIPANTS

This is an epidemiologic, multicenter, population-based study conducted in seven areas of Spain. A total of 4,035 men and women (age range, 40 to 69 years) who were randomly selected from a target population of 236,412 subjects participated in the study.

INTERVENTIONS

Eligible subjects answered the European Commission for Steel and Coal questionnaire. Spirometry was performed, followed by a bronchodilator test when bronchial obstruction was present.

RESULTS

The prevalence of COPD was 9.1% (95% confidence interval [CI], 8.1 to 10.2%), 15% in smokers (95% CI, 12.8 to 17.1%), 12.8% in ex-smokers (95% CI, 10.7 to 14.8%), and 4.1% in nonsmokers (95% CI, 3.3 to 5.1%). The prevalence in men was 14.3% (95% CI, 12.8 to 15. 9%) and 3.9% in women (95% CI, 3.1 to 4.8%). Marked differences were observed between sexes in smoking; the percentage of nonsmokers was 23% in men and 76.3% in women (p<0.0001). The prevalence of COPD varied among the areas, ranging from 4.9% (95% CI, 3.2 to 7.0%) in the area of the lowest prevalence to 18% (95% CI, 14.8 to 21.2%) in the area of the highest. There was no previous diagnosis of COPD in 78.2% of cases (284 of 363). Only 49.3% of patients with severe COPD, 11.8% of patients with moderate COPD, and 10% of patients with mild COPD were receiving some kind of treatment for COPD. Multivariate analysis showed that individuals had a higher probability of having received a previous diagnosis of COPD if they lived in urban areas, were of male gender, were > 60 years old, had higher educational levels, had > 15 pack-year smoking history, or had symptoms of chronic bronchitis.

CONCLUSIONS

COPD is a very frequent disease in Spain, and presents significant geographic variations and a very low level of previous diagnosis and treatment, even in the most advanced cases.

[Epidemiological study of chronic obstructive pulmonary disease in Spain (IBERPOC): prevalence of chronic respiratory symptoms and airflow limitation]

The prevalence of chronic respiratory symptoms and chronic airflow limitation (CAFL) was determined in a multicentric epidemiological study carried out in seven different areas of Spain. Based on a target population of 236,412 persons, a random census sample of 4,035 individuals between 40 and 69 years of age was chosen. Subjects answered several questionnaires and performed spirometric tests followed by a bronchodilation test if bronchial obstruction was detected. Respiratory symptoms were reported by 48% of the population (95% CI: 46.4-49.5%) with greater frequency of symptoms among men than women (55.2% versus 41%, p < 0.001). The following levels of prevalence of chronic symptoms were found: cough, 13.5% (95% CI: 12.5-14.6%); expectoration, 10.7% (95% CI: 9.7-11.6%); dyspnea after one flight of stairs, 10.4% (95% CI: 9.5-11.4%); and wheezing, 40.2% (95% CI: 38.7-41.7%). The prevalence of chronic bronchitis (CB) was 4.8% (95% CI: 4.1-5.4%) and was more frequent among men than among women (8.3% and 1.4%, respectively; p < 0.001). Asthma had been diagnosed previously in 4.9% (95% CI: 4.2-5.5%), more often in women than in men (5.8% and 3.8%, respectively; p < 0.003). CAFL was found in 10.6% (95% CI: 9.6-11.5%), 15.8% in men and 5.5% in women (p < 0.001). All respiratory symptoms except asthma were more frequent among smokers than among ex-smokers, and in turn were more common among ex-smokers than non-smokers. The frequency of symptoms increased in accordance with accumulated smoking. The prevalence of CB and CAFL was vastly different from one region to another. Multivariate analysis showed that factors associated independently with the appearance of CB were smoking, age over 60 years, male sex and having worked in industry. In conclusion, respiratory symptoms, including CB and CAFL, are common in the Spanish population. Smoking and amount of smoking are directly related to the frequency of such symptoms. Substantial differences were found in the prevalence of CB and CAFL among the regions where the study was performed.

[Epidemiological study of chronic obstructive pulmonary disease in Spain (IBERPOC): recruitment and field work]

Chronic obstructive pulmonary disease (COPD) is a large-scale social and health problem. Because prevalence studies have been performed only in certain areas of Spain, the Spanish Society of Pneumology and Chest Surgery initiated the IBERPOC study with the aim of determining the prevalence of COPD in several parts of the country. IBERPOC is a multicenter, population-based epidemiological study in which subjects have been selected randomly. Seven full-time pneumologists work full-time in seven different areas of Spain. A study of this nature involves a series of difficulties that should be taken into account at the time of planning studies of a similar nature. After 5,827 attempts to reach subjects, a total of 4,967 useful contacts were made, to provide 97.3% of the 5,104 contacts expected. Of those 4,967 useful contacts, 4,035 subjects completed interviews. Among the 932 refusals, 882 (94.6%) agreed to answer a short telephone questionnaire. The field work took 13 months to complete, 30% more time than had been anticipated. The rates at which subjects could not be traced differed from one zone to another, ranging between 5% and 30%; higher rates were attributable to the absence of telephone data in the corresponding census report. In one zone, the dispersion of the census population over a very large area supposed greater difficulty and delay in carrying out the study. In conclusion, the rate of participation and the time required for recruitment can be considered satisfactory. The performance of field work by trained, full-time pneumologists has been essential to the development and quality of the study. Similar epidemiological studies should consider problems derived from the lack of adequate census data, as well as to avoid defining areas of extreme population dispersion in order to facilitate field work.