Disability has become the most important component of the burden of disease.1 In 2010, low back pain and major depressive disorders were ranked as the third and fourth leading causes of disability worldwide, after HIV/AIDS and road injuries, according to disability adjusted life years (DALYs).1 Although DALYs help to compare the relative magnitude of the disease burden across diseases and countries, they might not adequately capture the welfare impact of some diseases, for instance mental disorders, as they have a large impact on functioning and quality of life.2–4 According to the World Report on Disability,5 infectious diseases (e.g., malaria, tuberculosis and sexually transmitted diseases); non-communicable diseases (e.g., arthritis, hearing disorders, asthma) and injuries (road traffic injuries, occupational injuries and violence) are important causes of health-related disability in developed countries.

The World Mental Health (WMH) Surveys Initiative was launched by the World Health Organization (WHO) to collect comparable data on the burden of mental disorders around the world.6 Two WHO-WMH reports3,4 have provided information on the individual and societal-level impact of the disability due to 19 physical and mental conditions in the general population. By means of the WHO-Disability Assessment Schedule 2.0,7 the full and the partial inability to perform daily activities, as measures of functional impairment, were assessed. Both reports have emphasized, in agreement with the Global Burden of Disease (GBD) 2010 study1 that back and neck pain, among physical conditions, and depression, among mental disorders, were the most burdensome non-communicable conditions worldwide.

In Europe, nearly 42 million persons of working-age from 15 European countries (16.4%) reported having a long-standing health problem or disability in 2002.8 However, good sources of data on disability are not available in all European countries and cross-country comparisons are limited due to methodological differences.9 While harmonization of data on disability among European countries are underway by the European Health Interview Survey, 2008 (EHIS), there is still limited comparable information about the disability burden of health conditions in the working-age population of Europe.

Here data from 10 European countries participating in the World Mental Health surveys initiative (EU-WMH)10,11 were analysed with two general objectives: first, to describe the distribution of disability in the population aged 18 to 64 years; and second, to examine the contribution of health conditions to disability. We analysed the contribution of mental disorders and physical conditions on two self-reported measures of disability: complete inability (i.e., full role limitation) and partial ability (i.e., partial role limitation) to perform daily activities in three European regions.

Sample characteristics are displayed in Table 2. Regions were similar in gender distribution (about 50-51% were women) and in mean age (40.2 years). Approximately one third of the participants reported not being married at the time of the interview (32.2%), with a significantly lower proportion of married participants in Central-Eastern Europe (26.8%). Completed high school or more varied from 92.7% in Central-Western to only 50% in Southern Europe. Unemployment also varied: from the lowest rate in Central Western Europe (26.5%) to the highest rate in Central-Eastern (48.8%). Almost one in ten individuals (9.5%) reported a full role limitation day and about 18.0%, a partial role limitation day in the previous month. Central-Western Europe was the region with more full and partial role limitation days.

About half of the sample (48.2%) had a health condition (Central-Western Europe, 51.1%; Southern, 45.8%; and Central-Eastern Europe, 42.7%) (Fig. 1). Physical conditions were three times more prevalent than mental disorders (43.9% vs. 11.9%, respectively). Prevalence of mental disorders varied among regions, from 14.3% in Central-Western, 10.1% in Southern, and 6.5% in Central-Eastern Europe. Regional differences were observed for arthritis (Central-Eastern, 22.1% compared to Central-Western and Southern Europe). Central-Eastern Europe showed marked differences in regard to cardiovascular diseases as a highly prevalent condition (15.1%), and headache/migraine (6.6%) and chronic pain disorders (11.5%) as low prevalence conditions, in comparison with the other two regions.

Figure 1.

Prevalence rates and 95% Confidence Intervals of health conditions by European regions (EU-WMH).

*Other physical conditions: cancer, neurological diseases, diabetes, or any digestive disorders (stomach or intestine ulcer or irritable bowel disorder).

a All three European regions showed statistically significant differences in the prevalence of health conditions (95%CI does not overlap).

b Central-Eastern Europe showed statistically significant differences in the prevalence of health conditions in comparison with Central-Western and Southern Europe (95%CI does not overlap).

c Central-Western Europe showed statistically significant differences in the prevalence of health conditions in comparison with Southern and Central-Eastern Europe (95%CI does not overlap).

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As shown in Figure 2, about 30% of individuals reporting health conditions had any role limitation. Among those with any role limitation due to health conditions, around 60% reported partial, 15% reported full, and 25% reported both. Role limitation, particularly partial limitation, was significantly higher among individuals with any mental disorder (43.3%), than among those with a physical condition (29.1%). Mental disorders categories presented similar proportion of any role limitation. Among physical conditions, insomnia and other physical conditions presented the highest while cardiovascular and respiratory the lowest proportion of any role limitation.

Figure 2.

Distribution of role limitation's categories by health conditions (EU-WMH). Error bars (95%CI) are calculated for any role limitation.

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Figure 3 shows the Population Attributable Fraction (PAFs) of full (Fig. 3 A) and partial (Fig. 3 B) role limitation for physical conditions and mental disorders. In the overall sample (black column) the PAFs for all the health conditions were 62.6% for full role limitation and 46.6% for partial role limitation. This PAF difference was statistically significant at the overall level but not within the regions. Figure 3 A shows that the PAFs of full role limitation were similar for both types of conditions (physical and mental). This was also the case in two of the regions, but not for Central-Eastern Europe (white column) where the PAF for full role limitation attributable to mental disorders was lower than that attributable to physical conditions. In Figure 3 B no statistically significant differences were observed across regions on the contributions from each type of disorder to partial role limitation, again, with the exception of Central-Eastern Europe.

Figure 3.

Full role limitation (A) and partial role limitation (B) expressed as population attributable fractions (PAFs) by European regions (EU-WMH).

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Table 3 presents PAFs of full and partial role limitation for each health condition and by region. Results should be interpreted as follows: of 100% of the role limitation reported by participants, depressive disorders contribute to explain 12.7% of full role limitation and 12.1% of partial role limitation in Europe. Overall, anxiety, depression, chronic pain and other physical conditions contributed the highest PAFs to full role limitation. While chronic pain, depression, arthritis, anxiety, insomnia, headache/migraines and other physical conditions had the highest PAFs of partial role limitation. In Central-Western and in Southern Europe, depression and anxiety were substantial contributors to full role limitation. In Southern Europe, mental disorders also significantly contributed to partial role limitation. In Central-Eastern Europe almost all physical conditions, particularly cardiovascular diseases and chronic pain, contributed importantly to full and partial role limitation. Chronic pain was the health condition that substantially and consistently contributed to full and to partial role limitation in all European regions.

Our paper has four major findings. First, about two-thirds of the total full role limitation and about one-half of the partial role limitation are associated with nine health conditions in Europe. Theoretically, role limitations could be largely reduced by treating or successfully preventing these nine health conditions. Other burdensome health conditions not included in this study (for instance, hearing loss and visual impairment),5 as well as non-health related determinants (work-related and non-work related factors18,19) could cause role limitations left unexplained in this study. Second, chronic pain was the single condition that contributed the most to both disability measures in all European Regions. This is very consistent with the Global Burden of Disease Study results,1 in which low back pain is the leading cause of disability in Europe, and with previous studies reporting that musculoskeletal conditions, especially back and neck pain, are the most common cause of physical disability in Western countries.1 Third, regional differences were observed: depressive and anxiety disorders were important contributors to full and to partial role limitation in Central-Western and Southern Europe, while in Central-Eastern Europe cardiovascular diseases and headache/migraine were more important contributors. Previous studies have also reported that mental disorders represent a substantial burden in some European countries20–22 and in other countries.23 And fourth, Central-Eastern Europe was the region in which mental disorders contributed the lowest share of full and partial role limitation. This finding is in contrast with the GBD study, which ranked depression as one of the ten leading causes of disability in Bulgaria and in Romania. Reasons for this difference are not easy to grasp from our data, but we speculate with possible explanations below.

Our analysis was restricted to a population sample of working age individuals (18-64 years), thus, while this is not a sample of workers, full and partial role limitation estimates might be interpreted as proxy measures of absenteeism and presenteeism, respectively. Accordingly, health conditions have a much larger impact on absenteeism than on presenteeism. This is because, in general, other non-health related factors frequently account for work performance.18,19 Work-related factors (e.g., shift work, physical work, employment position, among others) together with non work-related characteristics (e.g., family life, financial situation, adverse life events, among others) have also been shown to be relevant in explaining work performance. Nevertheless, the proportion of reduced functioning explained by common and treatable health conditions is far from negligible. Moreover, given that partial disability predicts future full disability,24 our findings carry important policy-making implications. A previous study25 of over one million workers showed that the cost of productivity losses associated to health conditions would be about 40% of the medical costs generated by the same health conditions. Thus, reducing the impact of prevalent disorders should be a priority in occupational health policies in all European regions.

Chronic pain, anxiety, and depression explained almost half of all health-related full role limitation reported in Central-Western (46.3%) and in Southern Europe (53.8%); and chronic pain, cardiovascular diseases and headache/migraines did so in Central-Eastern Europe (48.0%). The most important cross-regional difference was the small proportion of disability explained by mental disorders in Central-Eastern Europe in comparison with the other two regions. WMH survey data are cross-nationally comparable as they were assembled using a standardized protocol for sampling, interviewing, coding and analysing.15 So, it is likely that this cross-regional difference might be explained by reasons other than methodological issues. All health conditions that significantly contributed to full role limitation in our study were respectively listed among the top-ten highly disabling conditions in the 2010 GBD study, except for mental disorders in Central-Eastern Europe. In terms of DALYs, major depressive disorders ranked eighth and sixth as the most disabling condition in Bulgaria and Romania, respectively. Similarities and differences between 2010 GBD study and WMH have been extensively discussed26 but, in general, DALYs and PAFs are population-based disability measures that can be compared. It is known that prevalence and disability are not directly correlated; in particular, mental disorders are conditions with low prevalence but associated with large limitations in functioning.21 However, post hoc analyses of our data (not presented) showed a significantly lower proportion of partial role limitation in Romania compared to other countries with low prevalence of mental disorders (Italy and Germany). We speculate that specific cultural traits of the Romani population could account for this difference27,28 that fosters an underestimation of functional limitations associated with health conditions. Such underestimation would lead to underreporting functional limitations, resulting in measurement bias (i.e., a possible differential item functioning). Future research should address these country-specific differences in order to elucidate the true burden of mental disorders in Central-Eastern countries.

The impact of co-morbid conditions on health status is usually sub-additive.29 This could imply that to accomplish a more substantial decrease of the impact of co-morbid conditions on disability, all conditions, not only one in particular, should be addressed. We tested this hypothesis by including the number of co-morbid conditions in all models. For full role limitation, the coefficient of the number of co-morbid conditions was negative and statistically significant, while for partial limitation, the coefficient was non-significant. Our results would therefore be consistent with findings reported by Alonso et al.29 Nevertheless, we are aware that a simple co-morbidity count term is not the optimal way of controlling for co-morbidity: in addition to consider all co-morbid conditions at once, as we did here, it would also be necessary to consider which co-morbidity patterns are associated to higher or lower decrements in health. A previous study30 showed that depression in combination with certain chronic conditions (asthma, diabetes, angina) produced a greater decrement in health than any of these conditions alone or depression alone. Further exploration of patterns of chronic conditions and impact on disability is necessary.

Notwithstanding these limitations, our results are relevant for health policy, as most of these health conditions are treatable, so the large role limitation impact associated to them might be avoidable. They are also important for research, in particular about the differences in prevalence and in associated disability found in countries from Central-Eastern Europe.

Alberto Ruano-Ravina.

The corresponding author on behalf of the other authors guarantee the accuracy, transparency and honesty of the data and information contained in the study, that no relevant information has been omitted and that all discrepancies between authors have been adequately resolved and described.

This paper has 14 authors as the WMH Consortium's agreement specify in its publication policy the need of having one co-author from each of the participating countries. This policy is based on the crucial contribution to study design, data collection, pooling and harmonization, as well as their input in the manuscript preparation.

All authors have participated actively in the study, and have read and approved the submitted manuscript. G. Barbaglia, N.D. Adroher, J. Alonso and G. Vilagut were involved in the conception and design of the study, the analysis and interpretation of data and critically reviewed the manuscript. G. Barbaglia wrote the manuscript, and N.D. Adroher, G. Vilagut, J. Alonso, S. Florescu and R. de Graaf made substantial contributions to it. R. Bruffaerts, B. Bunting, J.M. Caldas de Almeida, S. Florescu, G. de Girolamo, R. de Graaf, J.M. Haro, H. Hinkov, V. Kovess-Masfety and H. Matschinger participated in the acquisition of data, critically reviewed the manuscript and provided final approval for the manuscript submitted.

The ESEMeD project is funded by the European Commission (contracts QLG5-1999-01042; SANCO 2004123 and EAHC 20081308), the Piedmont Region (Italy), Fondo de Investigación Sanitaria, Instituto de Salud Carlos III, Spain (FIS 00/0028), Ministerio de Ciencia y Tecnología, Spain (SAF 2000-158-CE), Departament de Salut, Generalitat de Catalunya, Spain, Instituto de Salud Carlos III (CIBER CB06/02/0046, RETICS RD06/0011 REM-TAP), and other local agencies and by an unrestricted educational grant from GlaxoSmithKline.

We thank the WMH staff for their assistance with instrumentation, fieldwork, and data analysis. A complete list of WMH funding support and publications can be found at: http://www.hcp.med.harvard.edu/wmh.

This work was supported by the European Commission [QLG5-1999-01042, SANCO 2004123, EAHC 20081308], the Piedmont Region (Italy), Fondo de Investigación Sanitaria, Instituto de Salud Carlos III, Spain [FIS 00/0028-02], Ministerio de Ciencia y Tecnología, Spain [SAF 2000-158-CE], Departament de Salut, Generalitat de Catalunya, Spain [AGAUR 2014 SGR 748 AGAUR 2009 SGR 1095], and other local agencies and by an unrestricted educational grant from GlaxoSmithKline. ESEMeD is carried out in conjunction with the World Health Organization World Mental Health (WMH) Survey. G. Barbaglia was supported by Ministerio de Ciencia e Innovación Rio Hortega grant [CM 10-00099]. No funding bodies had any role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

None.