SIR,
Dr Anthony David and colleagues (1) cite our paper (2) as one that makes inflated claims about the chtionic fatigue syndrome.
We first reported retrospectively an association between antibodies to coxsackie virus B and a group of symptoms similar to those previously described as myalgic encephalomyelitis. (3) We were faced with an ever increasing clinical problem of which we had little understanding, and the prospective investigation of coxsackie virus B antibody titres in these patients seemed a reasonable step forward. No widely accepted definition of the chronic fatigue syndrome existed in 1983, and we did not attempt to define it. We approached the problem from the opposite direction in that we had a definable test and we tried to show what happened to the results of this test in a group of ill patients.
Since 1983 much research into this syndrome has been carried out. It has taken a long time for a consensus to be agreed defining the syndrome. We believe that today’s definition that the syndrome cannot be diagnosed before six months has elapsed is acceptable. In our study 72% of our patients were still unwell six months into the illness.
The comparison made by Dr David and colleagues of their paper with ours is invalid. They questioned 611 general practice attenders whereas we reported on a group of 140 patients presenting over six months with what we believe to be the same illness.
In retrospect we think that what we observed was the slow spread of an infective agent through our town in 1983 and through neighbouring towns in our district in 1984 and 1985. The clinical syndrome coincided with a rise in the prevalence of coxsackie virus B antibodies in the general population from 10-12% in 1973-84 (we found 25% in 1983) to 55% in 1985-6. (4) Since then our clinical impression has been one of a return to normal; we see occasional new cases but not as many as in 1983.
The prevalence of this condition seems to depend on the activity of an infective agent of some kind, be it viral or otherwise, in the area of study at the time, and further research is made difficult by the wide fluctuations of prevalence that will be found from place to place and from time to time.
~B D CALDER
~P J WARNOCK Helensburgh G84 8BW
1 David A, Pelosi A, McDonald E, et al. Tired, weak, or in need of rest: fatigue among general practice attenders. BMJ 1990;301:1199-202. (24 November.)
2 Calder BD, Warnock PJ, McCartney RA, Bell EJ. Coxsackie B viruses and post-viral syndrome J R Coll Gen Pract 1987;37: 11-4.
3 Calder BD, Warnock PJ. Coxsackie B infections in Scottish general practice. J R Coll Gen Pract 1984;34:15-9.
4 Miller NA, Carmichael HA, Calder BD, et al. Antibody to coxsackie B virus in diagnosing postviral fatigue syndrome. BMJ (in press).
Source: B D Calder and P J Warnock. Chronic fatigue syndrome. BMJ. 1991 Jan 19; 302(6769): 181. PMCID: PMC1668832 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1668832/