The prevalence, burden and risk factors associated with chronic obstructive pulmonary disease in Commonwealth of Independent States (Ukraine, Kazakhstan and Azerbaijan): results of the CORE study

Abstract

Background: In the Commonwealth of Independent States (CIS) countries the epidemiology of chronic obstructive pulmonary disease (COPD) is poorly characterized. The objective of this analysis is to present the prevalence, burden and risk factors associated with COPD in three CIS countries as part of the CORE study (Chronic Obstructive Respiratory Diseases), the rationale and design of which have been described elsewhere.

Methods: A total of 2842 adults (≥18 years) were recruited (964 in Ukraine, Kiev, 945 in Kazakhstan, Almaty and 933 in Azerbaijan, Baku) between 2013 and 2015 during household visits. Two-step cluster randomization was used for the sampling strategy. All respondents were interviewed about respiratory symptoms, smoking status and medical history, and underwent spirometry with bronchodilator. COPD was defined as (i) “previously diagnosed” when the respondent reported that he/she had previously been diagnosed with COPD by a doctor, (ii) “diagnosed by spirometry” using the GOLD criteria (2011) based on spirometry conducted during the study (FEV₁/FVC < 0.70), and (iii) “firstly diagnosed by spirometry”, when the patient had received the COPD diagnosis for the first time based on the spirometry results obtained in this study.

Results: The prevalence of “previously diagnosed” COPD was 10.4, 13.8 and 4.3 per 1000, and the prevalence of COPD “diagnosed by spirometry” was 31.9, 66.7 and 37.5 per 1000 in Ukraine, Kazakhstan, and Azerbaijan, respectively. Almost all respondents with COPD were diagnosed for the first time during this study. A statistically significant relationship was shown between smoking and COPD in Kazakhstan (odds ratio, OR: 3.75) and Azerbaijan (OR: 2.80); BMI in Ukraine (OR: 2.10); tuberculosis in Ukraine (OR: 32.3); and dusty work in Kazakhstan (OR: 2.30). Co-morbidities like cardiovascular diseases and a history of pneumonia occurred significantly (p < 0.05) more frequently in the COPD population compared to the non-COPD population across all participating countries. For hypertension, this was the case in Ukraine and Azerbaijan.

Conclusion: In CIS countries (Ukraine, Kazakhstan and Azerbaijan), the prevalence of COPD “diagnosed by spirometry” was significantly higher than the prevalence of previously diagnosed COPD. Compared to many other countries, the prevalence of COPD seems to be relatively low in CIS countries. Factors such as limited funding from the government; lack of COPD knowledge and the attitude within the population, and of primary care physicians; as well as low access to high-quality spirometry may play a role in this under-diagnosis of COPD. The information provided in this paper will be helpful for healthcare policy makers in CIS countries to instruct COPD management and prevention strategies and to allocate healthcare resources accordingly.

Keywords: Azerbaijan; Chronic obstructive pulmonary disease (COPD); Kazakhstan; Prevalence; Risk factors; Ukraine.

Fig. 1

Point prevalence of COPD in the whole population. The prevalence was calculated per 1000 persons and expressed with 95% confidence intervals, for three COPD definitions: previously diagnosed COPD (when self-reported by the respondent while completing the study questionnaire); COPD diagnosed by spirometry (confirmed by spirometry results based on GOLD Guidelines (2011), i.e. FEV₁/FVC <  0.70), and firstly diagnosed COPD by spirometry (when the respondent was diagnosed with COPD for the first time based on spirometry outcomes)

Fig. 2

Point prevalence of COPD among respondents ≥40 years old. The prevalence was calculated per 1000 persons and expressed with 95% confidence intervals, for three COPD definitions: previously diagnosed COPD (when self-reported by the respondent while completing the study questionnaire); COPD diagnosed by spirometry (confirmed by spirometry results based on the GOLD guideline (2011), i.e. FEV₁/FVC <  0.70), and firstly diagnosed COPD by spirometry (when the respondent was diagnosed with COPD for the first time based on spirometry outcomes)

Fig. 3

Point prevalence of COPD (diagnosed by spirometry) by GOLD stage. The prevalence of various GOLD stages of COPD was calculated per 1000 persons and expressed with 95% confidence intervals, for COPD diagnosed by spirometry (confirmed by spirometry results based on GOLD Guidelines (2011), i.e. FEV1/FVC <  0.70). There were no respondents diagnosed with COPD III or IV GOLD stages in this study

Fig. 4

Point prevalence of COPD stratified by age. The prevalence of COPD was calculated per 1000 persons and expressed with 95% confidence intervals in three age groups: 18–39, 40–64, and ≥65 years old, for previously diagnosed COPD (when self-reported by the respondent while completing the study questionnaire) and COPD diagnosed by spirometry (confirmed by spirometry results based on GOLD Guidelines (2011), i.e. FEV₁/FVC <  0.70)

Fig. 5

Point prevalence of COPD stratified by gender. The prevalence of COPD was calculated per 1000 persons and expressed with 95% confidence intervals, among men and women, for previously diagnosed COPD (when self-reported by the respondent while completing the study questionnaire) and COPD diagnosed by spirometry (confirmed by spirometry results based on GOLD Guidelines (2011), i.e. FEV₁/FVC <  0.70)

Fig. 6

Association between risk factors and COPD diagnosed by spirometry. Odds ratios [OR] and 95% confidence intervals for OR are presented for each potential risk factor. Asterisk (*) denotes as statistically significant association between risk factor and COPD diagnosed by spirometry (p < 0.05). For tuberculosis in anamnesis, a significant association was found in Ukraine, but not included in the figure due to the high OR value: 32.393 (CI 4.403–238.330)