Comparison of first degree relatives and spouses of people with chronic tension headacheBMJ 1997; 314 doi: https://doi.org/10.1136/bmj.314.7087.1092 (Published 12 April 1997) Cite this as: BMJ 1997;314:1092
- Steen Østergaard, research fellowa,
- Michael Bjørn Russell, research fellowa,
- Lars Bendtsen, research fellowa,
- Jes Olesen, professora
- Correspondence and reprint requests to: Dr Russell
- Accepted 31 October 1996
Tension headache is known by virtually everyone. Most people have mild and infrequent attacks, but about 3% of the population have frequent attacks–chronic tension headache.1 Chronic tension headache often affects patients for a major part of their lives, causing considerable personal and socioeconomic expense.2
The aetiology of chronic tension headache remains largely unknown. A genetic factor has not previously been suspected, although patients suffering from chronic tension headache commonly report a family history of the condition. We examined the familial occurrence of chronic tension headache in spouses and first degree relatives of probands with chronic tension headache in order to evaluate its possible genetic background.
Patients, methods, and results
We studied 122 consecutive probands meeting the International Headache Society's criteria for chronic tension headache.3 Probands had a clinical interview and a physical and a neurological examination by neurological residents (junior doctors). Spouses and first degree relatives aged 18 years or above were interviewed by telephone (SØ). The participation rate was 100% among spouses (93/93; some probands were unmarried or divorced) and 95% (377/396) among first degree relatives. The project was approved by the Danish ethics committees.
The risk of familial occurrence was assessed by estimating the population relative risk of the disease in specified groups of relatives.4 The risk was calculated as the probability that a relative is affected given that the proband is affected, divided by the probability that a random member of the population is affected. A family aggregation is implied when this risk ratio significantly exceeds 1.
The one year prevalence of chronic tension headache is 3%, 5% among female patients and 2% among male patients.1 The lifetime prevalence was estimated to be twice that of the one year prevalence. As the prevalence of chronic tension headache depends on age and sex, the value of the denominator was adjusted according to the distribution of age and sex in the group of relatives studied; 95% confidence intervals were calculated by standard methods.
Table 1) shows the risk of chronic tension headache among first degree relatives and spouses. In comparison to the general population, first degree relatives had a significantly increased risk of chronic tension headache, while spouses had no increased risk of chronic tension headache.
This is the first family study of chronic tension headache. Our main result was that first degree relatives of probands with chronic tension headache had more than three times the risk of chronic tension headache than the general population.
An increased family risk can be caused by genetic or environmental factors. Because probands and spouses in part share their environment but differ in genetic constitution, the risk of chronic tension headache in spouses was used to elucidate the relative role of genetic and environmental factors. As first degree relatives had a significantly increased risk of chronic tension headache and spouses had no increased risk, our results support the importance of genetic factors in chronic tension headache.
Funding: No additional funding.
Conflict of interest: None.