Disability pension among patients undergoing coronary revascularisation

Background: Cardiovascular disease (CVD) is the main cause of death both in Sweden as well as globally, and represents a major public health problem also regarding impaired physical capacity and work disability. After musculoskeletal and mental diagnoses CVD is the third largest diagnostic group for disability pension (DP) in Sweden. Annually about 10 000 working-aged individuals undergo coronary revascularisation, i.e., coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI). These are established and well-documented interventions, resulting in symptom reduction, improved physical capacity, and among some patient groups, lower mortality. Coronary revascularisation could, hence, prevent early labour market exit. However, scientific knowledge is scarce regarding DP among patients with coronary revascularisation. The aim was to study general and diagnosis-specific DP, and its association with all-cause and CVD mortality among workingaged women and men with a first coronary revascularisation in 1994-2006, accounting for socio-demographic and medical factors.

Methods: Nationwide, population-based, cross-sectional and prospective cohort register studies were conducted. All, 78 153 patients, 30-65 years of age at time of their first coronary revascularisation in 1994-2006 in Sweden, were identified using the SWEDEHEART register, with information on all such interventions as well as patient characteristics, indication, date and type of intervention, and diabetes. Information on socio-demographic and medical factors was linked at individual level from nationwide registers held by the Social Insurance Agency, the National Board of Health and Welfare, and the Statistics Sweden. Logistic regression analyses were performed to estimate the probability of being on DP at the time of a first intervention (study I) and Cox regression analyses were performed to estimate the risk of being granted DP (study II), or the risk of all-cause mortality (study III) or allcause and CVD mortality (study IV) within five years following a first intervention.

Results: At the time of the coronary revascularisation, 24% were on DP; sixty two percent had been on DP for at least four years before intervention. The largest DP-diagnostic group was musculoskeletal diagnoses. The odds ratio for DP was higher among: CABG-patients, women, older individuals, lower level educated, foreign-born, individuals living in smaller communities and individuals with another indication for PCI than acute coronary syndrome or stable angina pectoris (study I). Within five years following the intervention, 32% had been granted DP. The hazard ratio for DP was higher among: CABG-patients, women, individuals with in-patient care for mental diagnoses (except for women, CABG), or musculoskeletal diagnoses in the five years before the intervention, with ≥180 sick-leave days in the year before the intervention, with diabetes at the intervention, and individuals with ≥1 re-intervention within the five following years (study II). Four percent died within five years following coronary revascularisation, most due to CVD. DP at the time of the intervention was associated with higher risks of mortality five years following intervention (study III). The mortality risk was higher among all the studied DP-diagnostic groups (CVD, musculoskeletal, and mental diagnoses) compared with no DP at the time of the intervention, and did not differ between the DP diagnoses (study IV).

Conclusions: A quarter of the patients already had DP at the time of CABG or PCI, a majority for at least 4 years before the intervention. In addition, the largest DP-diagnostic group was musculoskeletal diagnoses. One third was granted DP within a five-year followup. The mortality risk was higher both with all-cause and diagnosis-specific DP which could not be explained by the studied socio-demographic and medical factors. No differences in mortality were found between most of the studied DP-diagnostic groups; also musculoskeletal diagnoses were associated with higher five-year mortality. More detailed knowledge regarding these associations is needed.

List of scientific papers

I. Zetterström K, Voss M, Alexanderson K, Ivert T, Pehrsson K, Hammar N, Vaez M. Prevalence ofall-cause and diagnosis-specific disability pension at the time of first coronary revascularisation: A population-based Swedish cross-sectional study. PLoS ONE 2014:10(1): e0115540.
https://doi.org/10.1371/journal.pone.0115540

II. Zetterström K, Vaez M, Alexanderson K, Ivert T, Pehrsson K, Hammar N, Voss M. Disability pension after coronary revascularization: A prospective, nationwide, register-based Swedish cohort study. European Journal of Preventive Cardiology, 2015, 22(3): 304-311.
https://doi.org/10.1177/2047487313518472

III. Zetterström K, Voss M, Alexanderson K, Ivert T, Pehrsson K, Hammar N, Vaez M. Disability pension at the time of coronary revascularisation is associated with higher five-year mortality: A prospective, nationwide, register-based, Swedish cohort study. 2015 [Submitted]

IV. Zetterström K, Voss M, Alexanderson K, Ivert T, Pehrsson K, Hammar N, Vaez M. Associations between diagnosis-specific disability pension at the time of coronary revascularisation and mortality; A Swedish nationwide, population-based prospective cohort study. 2015 [Submitted]