The prevalence of chronic obstructive pulmonary disease in Maastricht, the Netherlands

  • Lowie E.G.W. Vanfleteren
    Correspondence
    Corresponding author. Program Development Centre, CIRO+, Centre of Expertise for Chronic Organ Failure, Hornerheide 1, 6085 NM Horn, The Netherlands. Tel.: +31 475587644.
    Affiliations
    Program Development Centre, CIRO+, Centre of Expertise for Chronic Organ Failure, Horn, The Netherlands

    Department of Respiratory Medicine, Maastricht University Medical Centre (MUMC+), Maastricht, The Netherlands
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  • Frits M.E. Franssen
    Affiliations
    Program Development Centre, CIRO+, Centre of Expertise for Chronic Organ Failure, Horn, The Netherlands
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  • Geertjan Wesseling
    Affiliations
    Department of Respiratory Medicine, Maastricht University Medical Centre (MUMC+), Maastricht, The Netherlands
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  • Emiel F.M. Wouters
    Affiliations
    Program Development Centre, CIRO+, Centre of Expertise for Chronic Organ Failure, Horn, The Netherlands

    Department of Respiratory Medicine, Maastricht University Medical Centre (MUMC+), Maastricht, The Netherlands
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Open ArchivePublished:February 20, 2012DOI:https://doi.org/10.1016/j.rmed.2012.01.008

      Summary

      Background

      Chronic obstructive pulmonary disease (COPD) is an increasing public health problem worldwide. Although epidemiologic data on COPD are important to raise awareness of the burden of disease, there are no actual spirometry-based data on the prevalence of COPD in the Netherlands.

      Methods

      Using the Burden of Obstructive Lung Disease (BOLD) protocol and study design, a population-based sample of adults, aged ≥40 years, in the area of Maastricht, the Netherlands was surveyed. Post-bronchodilator spirometry and questionnaires with information on smoking history and reported respiratory disease were collected. COPD was defined as post-bronchodilator FEV1/FVC ratio < 0,7 (GOLD) or < the lower limit of normal (LLN) (95th percentile) of the population distribution for FEV1/FVC. Data were statistically weighted for the total number of people in the Maastricht population.

      Results

      Overall prevalence of COPD was 24%, and was higher for men (28.5%) than for women (195%). (unweighted p = 0.002) The prevalence of GOLD stage 2 or higher COPD was 10%. The prevalence of LLN-defined COPD was 19% and 10% for stage 2 or higher. Overall prevalence of current smoking was 23%. The prevalence of COPD increased with age and amount of pack-years, although 14% of never smokers fulfilled spirometric criteria for COPD. The prevalence of doctor-diagnosed COPD was only 8.8%.

      Conclusion

      Almost one quarter of the Maastricht population aged ≥40 years had COPD. Considering the ageing population and still an important smoking prevalence, this burden is bound to increase and imposes great demands to public health care and society in the Netherlands.

      Keywords

      Introduction

      Chronic obstructive pulmonary disease (COPD) is a serious and increasing public health problem throughout the world. Although preventable, COPD cannot be cured and causes high levels of disability. This imposes increasing demands on regional health care systems and a growing economic burden on society. Lost productivity due to COPD has a particularly high impact on the economy, accounting for 50% of the overall COPD-related societal cost in the Netherlands.
      • Wouters E.F.M.
      The societal impact of COPD in North America and Europe: an economic analysis of the confronting COPD survey.
      • Wouters E.F.
      The burden of COPD in The Netherlands: results from the Confronting COPD survey.
      Although epidemiologic data on COPD are important to raise awareness of the burden of this disease, country-specific studies on the current and future impact of COPD in the Netherlands are scarce. Available date are mostly based on physician’s diagnosis of ‘COPD’, ‘chronic bronchitis’ or ‘lung emphysema’.

      Hoeymans N, Melse JM, Schoemaker CG (red). Gezondheid en determinanten. Deelrapport van de Van gezond naar beter. RIVM report 270061006. RIVM 2010. http://www.rivm.nl/bibliotheek/rapporten/270061006.html.

      Moreover, COPD tends to be underdiagnosed and undertreated by healthcare professionals in the Netherlands.
      • Wouters E.F.
      The burden of COPD in The Netherlands: results from the Confronting COPD survey.
      Therefore, the aim of the present study was to assess the prevalence of COPD and its risk factors in the general population aged 40 years and older in Maastricht, the Netherlands. To achieve both maximum accuracy and completeness of the survey as well as high-quality post-bronchodilator spirometry, the Burden of Obstructive Lung Disease (BOLD) protocol and study design were implemented.
      • Buist A.S.
      • Vollmer W.M.
      • Sullivan S.D.
      • Weiss K.B.
      • Lee T.A.
      • Menezes A.M.
      • Crapo R.O.
      • Jensen R.L.
      • Burney P.G.
      The burden of obstructive lung disease Initiative (BOLD): rationale and design.

      Methods

      A population-based cross-sectional study of the prevalence of COPD in the area of Maastricht, the Netherlands was conducted from October 2007 till March 2009. The BOLD protocol and definitions of smoking history were followed.
      • Buist A.S.
      • Vollmer W.M.
      • Sullivan S.D.
      • Weiss K.B.
      • Lee T.A.
      • Menezes A.M.
      • Crapo R.O.
      • Jensen R.L.
      • Burney P.G.
      The burden of obstructive lung disease Initiative (BOLD): rationale and design.
      Municipal administrators sampled adults aged ≥40 years at random from the population. Following a recruitment letter, subjects were contacted by phone and a clinic visit was scheduled. All participants gave written informed consent. The study was approved by medical ethical committee of Maastricht University Medical Centre.
      COPD was defined according to GOLD
      • Rabe K.F.
      • Hurd S.
      • Anzueto A.
      • Barnes P.J.
      • Buist S.A.
      • Calverley P.
      • Fukuchi Y.
      • Jenkins C.
      • Rodriguez-Roisin R.
      • van Weel C.
      • Zielinski J.
      Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: GOLD executive summary.
      or according to the lower limit of normal (LLN), which is beneath the 95th percentile of population distribution for the FEV1/FVC ratio according to NHANES.
      • Hankinson J.L.
      • Odencrantz J.R.
      • Fedan K.B.
      Spirometric reference values from a sample of the general US population.
      COPD stage 2 or higher was defined as FEV1 <80% of predicted. Doctor-diagnosed COPD was defined as a self-reported physician’s diagnosis of chronic bronchitis, emphysema, or COPD.
      Prevalence estimates for the overall Maastricht population, as well as for subgroups defined by gender and either age or pack-years of cigarette smoking were calculated using the Stata package (Stata Corporation, College Station, TX USA). Weighting class adjustments were made to adjust for differential response rates for the eight categories defined by gender and age, to assure that the estimated prevalences and SEs properly reflect the sampling design. Differences within the study sample were calculated on the unweighted dataset, using two-sided p-value based on Pearson chi-square test.

      Results

      A total of 634 of 1345 subjects (47%) selected for recruitment signed informed consent. This is 48% of the 1323 subjects whom the site attempted to contact (22 were ineligible), and 55% of the 1147 succesfully contacted subjects. Compared to participants subjects who denied participation or could not be reached were more prevalent in the 70 + age category (p < 0,05), but there were no differences in gender (p > 0.05) or smoking history (p > 0.05). Forty-two subjects were excluded because of unacceptable post-bronchodilator spirometry. These were more frequently current smokers compared to 592 subjects included in the analyses (43% vs. 23%, p < 0,01). Baseline characteristics are listed in Table 1.
      Table 1Characteristics of subjects included in the analyses – results are for observed sample only and are not population estimates.
      No.592 (100%)
      Age
       40–49160 (27%)
       50–59182 (31%)
       60–69167 (28%)
       70+83 (14%)
      Gender
       Male300 (51%)
       Female292 (49%)
      Smoking status
       Current136 (23%)
       Ex252 (43%)
       Never204 (34%)
      Doctor diagnosed asthma60/591 (10%)
      Doctor diagnosed COPD, chronic bronchitis or emphysema48/591 (8%)
      Estimated population prevalence of GOLD- and LLN-defined COPD by age, gender and smoking status is presented in Table 2, Table 3. The estimated prevalence of doctor-diagnosed COPD was 8.8% (SE:1.2).
      Table 2Estimated Population Prevalence of GOLD stage 1 or higher, GOLD stage 2 or higher, LLN stage 1 or higher, LLN stage 2 or higher COPD by age and sex – Weighted po-pulation estimate, with SE shown in parenthesis.
      AgeMaleFemaleTotal
      GOLD 1 +40–499.0% (3.4)5.8% (3.0)7.4% (2.2)
      50–5927.4% (4.9)18.4% (4.1)22.9% (3.2)
      60–6937.0% (5.3)18.4% (4.2)
      P < 0.05 on the unweighted population sample.
      27.6% (3.5)
      70+51.2% (7.7)35.6% (8.2)41.6% (5.9)
      Total28.5% (2.8)19.5% (2.9)
      P < 0.05 on the unweighted population sample.
      23.7% (2.0)
      GOLD 2 +40–494.4% (2.6)1.2% (1.2)2.8% (1.4)
      50–5913.7% (3.8)8.2% (3.1)10.9% (2.4)
      60–6918.9% (4.4)6.9% (2.7)
      P < 0.05 on the unweighted population sample.
      12.8% (2.6)
      70+19.9% (6.3)15.6% (7.2)17.3% (5.0)
      Total13.2% (2.1)8.0% (2.3)
      P < 0.05 on the unweighted population sample.
      10.4% (1.5)
      LLN 1 +40–497.8% (3.2)14.0% (4.1)11.0% (2.6)
      50–5922.6% (4.6)18.4% (4.1)20.5% (3.1)
      60–6920.0% (4.5)16.1% (4.0)18.0% (3.0)
      70+33.6% (7.4)22.3% (7.7)26.6% (5.5)
      Total19.7% (2.4)17.8% (2.7)18.7% (1.8)
      LLN 2 +40–494.4% (2.6)3.5% (2.0)3.9% (1.6)
      50–5912.7% (3.7)8.2% (3.1)10.4% (2.4)
      60–6912.7% (3.7)6.9% (2.7)9.8% (2.3)
      70+19.9% (6.3)15.6% (7.2)17.3% (5.0)
      Total11.6% (2.0)8.6% (2.3)10.0% (1.5)
      a P < 0.05 on the unweighted population sample.
      Table 3Estimated Population Prevalence of GOLD stage 1 or higher, GOLD stage 2 or higher, LLN stage 1 or higher, LLN stage 2 or higher COPD by pack years and sex – Weighted population estimate, with SE shown in parenthesis.
      PackyearsMaleFemaleTotal
      GOLD 1 +Never smokers10.7% (3.5)16.2% (4.1)14.1% (2.8)
      0–1020.4% (5.6)12.0% (5.3)16.1% (3.8)
      10–2021.3% (6.3)20.9% (7.0)21.1% (4.7)
      20+51.0% (5.0)29.8% (6.7)
      p < 0.05 on the unweighted population sample.
      41.2% (4.0)
      Total28.5% (2.8)19.5% (2.9)
      p < 0.05 on the unweighted population sample.
      23.7% (2.0)
      GOLD 2 +Never smokers4.8% (2.5)2.0% (1.5)3.1% (1.3)
      0–108.3% (4.2)4.6% (3.4)6.4% (2.7)
      10–204.0% (2.8)7.0% (5.2)5.5% (3.0)
      20+26.4% (4.5)20.6% (6.7)23.7% (3.9)
      Total13.2% (2.1)8.0% (2.3)
      p < 0.05 on the unweighted population sample.
      10.4% (1.5)
      LLN 1 +Never smokers4.8% (2.5)10.0% (3.1)8.0% (2.2)
      0–1013.2% (4.8)9.4% (4.7)11.2% (3.4)
      10–2017.9% (5.9)19.0% (6.9)18.5% (4.5)
      20+37.5% (4.9)35.9% (6.7)36.7% (4.1)
      Total19.7% (2.4)17.8% (2.7)18.7% (1.8)
      LLN 2 +Never smokers3.8% (2.3)2.0% (1.5)2.7% (1.3)
      0–100.8% (4.2)6.3% (3.7)7.2% (2.8)
      10–202.3% (2.3)7.0% (5.2)4.6% (2.9)
      20+23.9% (4.4)21.8% (6.7)22.9% (3.9)
      Total11.6% (2.0)8.6% (2.3)10.0% (1.5)
      a p < 0.05 on the unweighted population sample.
      The estimated prevalence of current smoking was 23% (SE:1.8) and was similar for both sexes (Male 24% (SE:2.4); female 22% (SE:2.7)). The prevalence of ever smokers (overall 63% (SE:2.1)) was higher in men (70% (SE:2.7)) than in women 57% (SE:3.2)) (p < 0.001). The highest prevalence of ever smokers was in men, 60–69 years old and was 85% (SE:3.7). Thirty-one percent of the population ever smoked more than 20 pack-years. Of these subjects, 22% had at least GOLD stage 2 COPD and 11% had doctor diagnosed COPD.

      Discussion

      Using BOLD
      • Buist A.S.
      • Vollmer W.M.
      • Sullivan S.D.
      • Weiss K.B.
      • Lee T.A.
      • Menezes A.M.
      • Crapo R.O.
      • Jensen R.L.
      • Burney P.G.
      The burden of obstructive lung disease Initiative (BOLD): rationale and design.
      methodology, this study showed that the prevalence of GOLD-defined COPD in the general population aged 40 years and older in Maastricht, the Netherlands is 24%. Ten percent of population had COPD GOLD stage 2 or higher. Using the LLN to define COPD, still 19% had COPD and 10% had at least stage 2. The overall prevalence of GOLD-defined COPD was higher in men than in women. The estimated prevalence of current smokers was 23%.
      Based on five databases containing registrations of physician’s diagnosis of COPD, chronic bronchitis or lung emphysema in primary care, the state institute for public health and environment in the Netherlands (RIVM) estimated the prevalence of COPD in 2007 as 1.8% for men and 1.6% for women.

      Hoeymans N, Melse JM, Schoemaker CG (red). Gezondheid en determinanten. Deelrapport van de Van gezond naar beter. RIVM report 270061006. RIVM 2010. http://www.rivm.nl/bibliotheek/rapporten/270061006.html.

      This reported prevalence does not approach the magnitude reported in the present study and probably underestimated the real burden of COPD. Also in the present study, the prevalence of spirometric confirmed COPD was much higher than the prevalence of physician diagnosed COPD. Even the prevalence of at least GOLD stage 2 COPD in subjects who smoked more than 20 pack years (22%) was twice as high as the physician’s diagnosis of COPD in the same group (11%). This problem of underdiagnosis of COPD has been reported earlier.
      • Schirnhofer L.
      • Lamprecht B.
      • Vollmer W.M.
      • Allison M.J.
      • Studnicka M.
      • Jensen R.L.
      • Buist A.S.
      COPD prevalence in Salzburg, Austria: results from the burden of obstructive lung disease (BOLD) study.
      • Dirven J.A.
      • Muris J.W.
      • van Schayck C.P.
      COPD screening in general practice using a telephone questionnaire.
      In the “confronting COPD survey”
      • Wouters E.F.M.
      The societal impact of COPD in North America and Europe: an economic analysis of the confronting COPD survey.
      COPD was underdiagnosed and undertreated, in the Netherlands as well as in the six other participating countries. In the Netherlands, 19% of patients were undiagnosed despite having symptoms consistent with COPD.
      The prevalence of COPD increases with age and the amount of smoked pack-years. A fixed ratio for FEV1/FVC to classify COPD as proposed by GOLD
      • Rabe K.F.
      • Hurd S.
      • Anzueto A.
      • Barnes P.J.
      • Buist S.A.
      • Calverley P.
      • Fukuchi Y.
      • Jenkins C.
      • Rodriguez-Roisin R.
      • van Weel C.
      • Zielinski J.
      Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: GOLD executive summary.
      may lead to increasing false positive diagnosis of COPD with age, since FEV1/FVC physiologically reduces with age.
      • Hardie J.A.
      • Buist A.S.
      • Vollmer W.M.
      • Ellingsen I.
      • Bakke P.S.
      • Mørkve O.
      Risk of over-diagnosis of COPD in asymptomatic elderly never-smokers.
      This misclassification could be reduced by using the LLN for the FEV1/FVC ratio and this could possibly better distinct physiology from pathology. Using the LLN instead of the GOLD criterion to define COPD in subjects older than 70 years in this study population resulted in a reduction in COPD diagnosis from 42% to 27%. This was still substantially higher than in lower age-categories. Obviously the cumulative effect of smoking history and inhalational exposures influence airflow limitation in the elderly. Current and former smoking by oneself are clearly related to age, with older men (age 60–69 years) having stunning ever-smoking prevalence up to 85% This magnitude of ever-smoking has to mean that environmental tobacco exposure has also been substantial during the foregone decades before recognition of its harmfulness.
      • Callinan J.E.
      • Clarke A.
      • Doherty K.
      • Kelleher C.
      Legislative smoking bans for reducing secondhand smoke exposure, smoking prevalence and tobacco consumption.
      GOLD-defined COPD was found in 14% of persons who had never smoked. According to the LLN this was still 6%. Although never smokers were less likely to have COPD than ever smokers, never smokers nonetheless comprised one fifth of all subjects with COPD. Predictors of COPD in never smokers in the international BOLD cohort included age, education, occupational exposure, childhood respiratory diseases and BMI alterations.
      • Lamprecht B.
      • McBurnie M.A.
      • Vollmer W.M.
      • Gudmundsson G.
      • Welte T.
      • Nizankowska-Mogilnicka E.
      • Studnicka M.
      • Bateman E.
      • Anto J.M.
      • Burney P.
      • Mannino D.M.
      • Buist S.A.
      BOLD Collaborative Research Group. COPD in never smokers: results from the population-based burden of obstructive lung disease study.
      As generally seen among the BOLD sites throughout the world,
      • Buist A.S.
      • McBurnie M.A.
      • Vollmer W.M.
      • Gillespie S.
      • Burney P.
      • Mannino D.M.
      • Menezes A.M.
      • Sullivan S.D.
      • Lee T.A.
      • Weiss K.B.
      • Jensen R.L.
      • Marks G.B.
      • Gulsvik A.
      • Nizankowska-Mogilnicka E.
      BOLD Collaborative Research Group. International variation in the prevalence of COPD (the BOLD Study): a population-based prevalence study.
      also in the present study the overall prevalence of COPD was higher in men than in women. It has been predicted that the expected changes in smoking behaviour will result in a smaller increase of the projected prevalence in men and greater increase in women.
      • Feenstra T.L.
      • van Genugten M.L.
      • Hoogenveen R.T.
      • Wouters E.F.
      • Rutten-van Mölken M.P.
      The impact of aging and smoking on the future burden of chronic obstructive pulmonary disease: a model analysis in the Netherlands.
      Given men and women smoked equally in the present study, also in Maastricht the gender difference in the prevalence of COPD will equalise or possibly even reverse since women seem to be more vulnerable to develop COPD.
      • Foreman M.G.
      • Zhang L.
      • Murphy J.
      • Hansel N.N.
      • Make B.
      • Hokanson J.E.
      • Washko G.
      • Regan E.A.
      • Crapo J.D.
      • Silverman E.K.
      • Demeo D.L.
      • the COPDGene Investigators
      Early-onset COPD is associated with female gender, maternal factors, and African American Race in the COPDGene study.
      Already in the young-est age group, the prevalence of COPD according to the LLN tended to be higher in women than in men. This is consistent with the remarkably high incidence of COPD in the youngest women in the Rotterdam study.
      • van Durme Y.M.
      • Verhamme K.M.
      • Stijnen T.
      • van Rooij F.J.
      • Van Pottelberge G.R.
      • Hofman A.
      • Joos G.F.
      • Stricker B.H.
      • Brusselle G.G.
      Prevalence, incidence, and lifetime risk for the development of COPD in the elderly: the Rotterdam study.
      This study also has limitations. An important limitation is the lower than desirable response rate which causes uncertainty about the representativeness of the results. On the other hand we nearly reached the sample size of at least 300 men and 300 women as requested by the BOLD protocol. The prevalence of non-responders was higher in older age, but the sample individuals were weighted for the whole population of Maastricht. Unacceptable spirometry was more frequent in smokers. Another limitation was that other potential causes of airflow limitation than COPD (e.g. asthma, sarcoidosis, bronchiectasis, bronchiolar diseases) were not excluded. However, BOLD methodology was applied in the current survey, according to published methods and protocol. According to BOLD standards, COPD diagnosis was based on the lung function criteria without requiring documented exposure to a known causative agent.
      • Buist A.S.
      • McBurnie M.A.
      • Vollmer W.M.
      • Gillespie S.
      • Burney P.
      • Mannino D.M.
      • Menezes A.M.
      • Sullivan S.D.
      • Lee T.A.
      • Weiss K.B.
      • Jensen R.L.
      • Marks G.B.
      • Gulsvik A.
      • Nizankowska-Mogilnicka E.
      BOLD Collaborative Research Group. International variation in the prevalence of COPD (the BOLD Study): a population-based prevalence study.
      Although the Netherlands is a developed country and COPD is a preventable disease, a surprisingly high burden of COPD was found. With the ageing population and still an important smoking prevalence, this burden is bound to increase and impose great demands to public health care and society. The government faces the important task to continue the efforts to prevent the population from exposure to noxious substances, most importantly tobacco smoke. Health care professionals should give priority to a better evaluation and diagnosis of patients with COPD, as well as improved management of COPD and take an aggressive attitude on the reduction of tobacco smoking.

      Statement on conflict of interest

      This manuscript has been seen and approved by all authors, who took care to ensure the integrity of the work. There are no conflicts of interests or financial support to declare.

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