Abstract
Cluster headache is characterized by excruciatingly painful headaches which occur one or several times during the day. Little is known about the functional consequences of this severe headache form. We assessed health-related quality of life in 56 consecutive patients, 34 of whom were episodic cluster headache patients during an active period, and 22 had chronic cluster headache. All patients completed the Short Form-36 (SF-36). We found lower scores in the studied patients than in those reported in the general population for all SF-36 domains. For most scales the difference was significant (P < 0.0001, Student's t-test, Bonferroni correction). Our findings suggest that cluster headache has marked functional consequences even when appropriate treatments are used.
Introduction
Cluster headache is a primary headache characterized by excruciatingly painful unilateral headaches associated with ocular or nasal autonomic phenomena. The pain attacks tend to occur one or several times during the day and also at night. Two main clinical forms are recognized: episodic cluster headache, in which the attacks occur in periods lasting days or months, separated by headache-free periods lasting at least 2 weeks (remission phase); and chronic cluster headache, in which remissions are absent or last <14 days (1).
Over the last decade several studies have demonstrated that patients with primary headaches report markedly impaired quality of life and decreased ability to function. Standardized instruments such as the Short Form 36 and Short Form 20 (SF-36, SF-20) (2, 3), have often been used to assess health-related quality of life in headache (4–8). However, most studies have focused on migraine and more recently on chronic headaches; little attention has been paid to cluster headache (4).
The purpose of the study was to administer the SF-36 to a sample of patients with episodic or chronic cluster headache who were experiencing daily headaches, in order to investigate the impact on different quality of life domains and on patients’ sense of well-being.
Methods
The inclusion criteria were: (i) diagnosis of episodic or chronic cluster headache according to the criteria of the International Headache Society (1); (ii) patients reporting daily cluster headache attacks; (iii) patients who had not started prophylactic treatment when they were recruited or who had started prophylaxis but were still having daily headaches.
Fifty-six consecutive patients with these characteristics entered the study. The main characteristics of these patients are reported in Table 1. As expected, most were males. Thirty-four patients had episodic, and 22 had chronic cluster headache. Patients with the episodic form had been in active cluster period for 7–162 days (mean 45.1, SD 32.9).
Main characteristics of the studied cluster headache patients
In some patients prophylaxis with verapamil, lithium carbonate or steroids at the recommended doses (9) had started at the time they were studied, but with little benefit as they were still experiencing daily attacks. In most patients subcutaneous sumatriptan was effective in aborting pain attacks.
All patients completed the validated Italian version of the SF-36. Student's t-test with Bonferroni correction was used to compare patients’ scores for each SF-36 component with those in healthy subjects. We did not collect data from a sex- and age-matched sample but used the Italian normative data obtained by Apolone et al. from 1636 individuals of both sexes aged 23–68 years (10). The Wilcoxon rank sum test was used to compare SF-36 scores in episodic vs. chronic cluster headache patients.
Results
Cluster headache patients had lower scores than those in the Italian general population for all eight scales of the SF-36. For most scales (Bodily Pain, Role Functioning-Physical, General Health, Social Functioning, Role Functioning-Emotional and Mental Health) the difference was clinically significant (>5-point difference) (3). For these six scales scores were also significantly lower (P < 0.0001) than the Italian normative scores; while scores for Vitality (P = 1.59) and Physical Functioning (P = 2.28) did not differ significantly. No significant differences were found when SF-36 scores in episodic and chronic cluster headache patients were compared (Table 2).
SF-36 scores in cluster headache patients: comparison with Italian normative data (Student's t-test with Bonferroni correction) and comparison between episodic and chronic cluster headache patients (Wilcoxon rank sum test)
PF, Physical Functioning; RP, Role Functioning-Physical; BP, Bodily Pain; GH, General Health; VT, Vitality; SF, Social Functioning; RE, Role Functioning-Emotional; MH, Mental Health.
Discussion
Our results show that cluster headache is associated with a marked decrease in health-related quality of life during active periods. As expected, pain had a major influence on quality of life, as indicated by the low mean score for the Bodily Pain scale. Patients also had poor scores on the SF-36 scales, indicating the extent to which physical health and emotional problems interfere with work and social activities (Role Functioning-Physical, Role Functioning-Emotional, Social Functioning), and also in the scales that tap personal evaluation of health (General Health, Mental Health).
These findings are partially concordant with those reported by Solomon et al. in 1994 (4), who administered another standardized health-related quality of life instrument (the SF-20) to 208 North American headache patients, 13 of whom were cluster headache patients. The American study found that pain markedly influenced normal functioning, and that there were evident limitations in social functioning. However, health perception was preserved in Solomon et al.'s cluster headache patients, while our patients reported a more pervasive impact on their quality of life and sense of well-being. The differences between these studies may be due to the different instruments used (SF-36 vs. SF-20) and also to differences in patient characteristics. Thus, Solomon et al. studied a small population of cluster headache patients not all of whom were in active cluster period at the time of survey; furthermore, they were not using sumatriptan (as it was not available at the time the study was performed) and the use of prophylactic therapy was not specifically analysed (G. Solomon, personal communication).
By contrast, our patients were studied while experiencing daily attacks, and had high morbidity. As shown in Table 1, the mean illness duration was rather long (12.6 years), and some patients were resistant to prophylaxis: at least 29 (52%) had been taking specific prophylaxis for at least 7 days with little or no impact on daily headache frequency.
The high morbidity that characterized our series might be expected to result in overestimation of the self-perceived consequences of cluster headache. However, it is important to note that the majority (67% of episodic, and 77% of chronic cluster headache patients) were regular users of subcutaneous sumatriptan, which is able to reduce markedly the duration of individual attacks (9). In fact, resolution was generally reported within a few minutes compared with the normal duration of 15–180 min. The use of this medication could therefore have counterbalanced the effect of high morbidity in these patients.
To test this hypothesis we performed an exploratory analysis of the scores of each SF-36 scale of patients who had started prophylactic therapy compared with those of patients who had not started prophylaxis, and also of patients who were using sumatriptan as abortive drug and those who were not current users of this drug. In neither case did the Wilcoxon rank sum test reveal any significant difference.
In any event, our patients – all attending a specialist headache centre – are likely to be among the most severely affected by their illness, and the impact of the disorder on their health-related quality of life is likely to be greater than that on the general population of cluster headache patients. Ongoing research to compare SF-36 scores of episodic cluster headache patients during active cluster period and during remission, and to compare these patients with migraine patients, will lead to a better understanding of quality of life impairment in cluster headache. In conclusion, our findings shed light on the personal and social burden of cluster headache and suggest that this severe condition may cause marked functional consequences even when appropriate treatments are used.