Dr Christina SjostrandChristina Sjostrand, MD, PhD
Individuals with cluster headache are far more likely to have sickness absence and disability pension days in the workplace compared to their counterparts without the condition, new registry data suggest.1

Additionally, women—whom literature suggests are slightly less likely to experience cluster headache (although with more symptomatic presentation)2—were shown to have more sickness absence and disability pension days than men. This cohort, which consisted of 3240 patients, was 34% women.

Author Christina Sjostrand, MD, PhD, associate professor of neurology, and senior lecturer, Karolinska Institut, and colleagues noted that, often, studies assessing the happenings of sickness absence exclude information on disability pension, thus “giving a skewed picture of the actual effect of, as here, a disease on work incapacity. It is thus a great advantage that we could include both types of absence days, and relate them to those at risk, that is, in some measures exclude those not at risk for sickness absence.”

All told, patients with cluster headache had a combined 63.15 (95% CI, 58.84–67.45) days of sickness absence and disability pension, compared to the 34.08 (95% CI, 32.59–35.57) days for the matched control group (n = 16,200). The average number of sickness absence days in 2010 was 16.13 (95% CI, 14.05–18.20) among patients with cluster headache and 6.54 (95% CI, 5.97–7.11) among the comparator group.
 
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Women with cluster headache (23.71 [95% CI, 19.36–28.06]) had double the number of sickness absence days than that of men (12.41 [95% CI, 10.19–14.63]), and when adding in disability pension days, those numbers remained almost twice as high, at 83.71 (95% CI, 75.57–91.84) for women and 52.56 (95% CI, 47.62–57.51) for men.

“Patients with cluster headache with low education had more sickness absence + disability pension days compared to those with medium and high education,” Sjostrand et al wrote. Those with elementary education had 85.88 (95% CI, 75.34–96.42) days compared to those with high school (64.89 [95% CI, 58.82–70.97]) and college/university (41.42 [95% CI, 34.70–48.15]) education.

“Low education is a well-known sociodemographic risk factor for disability pension. In patients with cluster headache, all educational levels had higher numbers of sickness absence + disability pension days as well as for sickness absence days alone, compared to references,” The authors wrote, noting that the reason for this association between educational level and mean number of sickness absence + disability pension days is unclear

Additionally, those with cluster headache had significantly more sickness absence days in all ages compared to the reference group.

A notable strength of the work, Sjostrand and colleagues wrote, is the lack of inclusion of employment status among patients with cluster headache, meaning that irrespective of whether they had paid work, were unemployed, or were on parental leave, patients were included in analysis. The results, as such, were not impacted by the healthy worker effect, they noted.

In prior work, the group assessed sickness absence and disability pension in the same groups, finding, similarly, that those with cluster headache had a higher prevalence of full-time disability pension for all of 2010 (10.28%) compared to the reference group (5.82%). After excluding individuals on full-time disability pension the whole year, sickness absence rates were 6.88% and 4.12%, respectively.3

“Based on these large differences, we in this study deepened the analyses, focusing not only on the occurrence of sickness absence or disability pension but also on the magnitude of it, in terms of length and number of days—there is, of course, a large difference between having, for example, just a few days of sickness absence or 11 months of sickness absence,” Sjostrand and colleagues noted.
REFERENCES
1. Sjostrand C, Alexanderson K, Josefsson P, Steinberg A. Sickness absence and disability pension days in patients with cluster headache and matched reference. Neurology. 2020;00:1-9. doi:10.1212/WNL.0000000000009016
2. Wei DYT, Ong JJY, Goadsby PJ. Cluster Headache: Epidemiology, Pathophysiology, Clinical Features, and Diagnosis. Ann Indian Acad Neurol. 2018;21(Suppl 1):S3–S8. doi: 10.4103/aian.AIAN_349_17.
3. Steinberg A, Josefsson P, Alexanderson K, Sj¨ostrand C. Cluster headache: Prevalence, sickness absence, and disability pension in working ages in Sweden. Neurology. 2019;93:e404–e414.