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I read the study of Morgan et al on social deprivation and prevalence of epilepsy and associated health usage1 with great interest and would like to add some remarks from my experience in the most impoverished region of the United States, near the Mississippi Delta. I would caution that it is especially in a poor and traumatised population, extremely difficult to differentiate between true electrical events and non-epileptic (or pseudo) seizures.2 We have known since Charcot about the correlation between psychological traumatic states, to which poverty is intimately related and conducive, and “hysterical” seizures.3-5 There is a substantial comorbidity of epileptic and non-epileptic seizures.2 In fact, what I see here in Mississippi is more often than not a mixture of both and without proper, expensive testing, such as video EEG, it is sometimes impossible to make the difference. Because of the way the data were collected, it is difficult to know from the paper of Morganet al 1 whether pseudoseizures were properly taken into account when assessing the prevalence of epilepsy. The same caveat applies to the ascertainment of psychiatric comorbidity. A thorough neuropsychiatric screening of the clientele of an epilepsy clinic would disclose a much higher psychiatric comorbidity than the record linkage used here. Because of the way neurologists are trained, at least in the United States, most psychiatric comorbidity in neurology patients in general probably goes undiagnosed.
What the usage data of Morgan et al do show is how vain the treatment of neurological illness remains without addressing its social ecology. This certainly is true in Wales as well as in Mississippi.
The authors reply:
We thank Preter for his interest in our paper and for his comments identifying the problems associated with correctly diagnosing epilepsy. As we have indicated in the paper, these problems are intensified by record linkage techniques with the possibility of both false positive and false negative results. We discussed in some detail the issue of false negatives as we think this to be the greater problem within our study and so Preter's comments about false positives, particularly pseudoseizures, are most useful. Patients with pseudoseizures, however, will still place a demand on epilepsy services and therefore remain an issue in the allocation of resources within areas of high social deprivation.
We also accept that our ascertainment of psychiatric morbidity will be skewed towards the more severe forms of psychiatric comorbidity as, by our methodology, they will have to have come into contact with secondary care services. It is, however, these patients, excluded from our second analysis, who will have the greatest influence upon social and material deprivation.
We think, however, that despite these caveats, the findings of the study remain valid. As is often the case, a record linkage study raises as many questions as it answers and more detailed research is required in this area.