QATAR MEDICAL JOURNAL
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VOL. 1 3 / N O . 1 / JUNE 2004
ORIGINAL
STUDY
Epidemiology and Etiology of Intractable Epilepsy in Qatar Al Hail H., Sokrab T., Hamad A., Kamran S., Hamad A,A/R., and Khalid A. Neurology Section, Department of Medicine, Hamad Medical Corporation Doha, Qatar
Abstract: The medical records of 219 epileptic patients seen over a period of eight years were reviewed to determine the incidence and causes of intractable epilepsy amongst adults in Qatar: The incidence rate of hospital admission with uncontrolled epilepsy was calculated as 25per 100,000persons. Thirty-nine patients (18%) fulfilled the criteria for IE and the incidence of IE could be approximated at 4.5 per 100,000 persons. In the native Qatari population the approximated incidence of IE would be 1 in 100,000 persons per year, while in the expatriate population the rate would be 3.5 per 100,000persons per year. The most common type of IE was idiopathic generalized epilepsy (75%) followed by symptomatic epilepsy (19%) and temporal lobe epilepsy (6%). To calculate the crude incidence of epilepsy in Qatar, the records were reviewed of 1217patients (aged 13-85 years) visiting the outpatient department or admitted to hospital because of a newly diagnosed epilepsy during the calendar year, 1st January-31st December 2001. These figures were extrapolated to an approximation of an incidence of 174 in 100,000 persons per year. Keywords:
Epidemiology, Incidence, Epilepsy, Intractable
zure control cannot be achieved despite adequate trial of available AEDs(4,5). Such intractable epilepsy (IE) imposes considerable socio-economic and psychological constraints on the individual patient and casts a substantial burden on health and welfare resources(6). Qatar is a peninsula of about 11,000 km2 located on the western coast of the Arabian Gulf. At the time of this study its population was 522,000 of whom about 70% were expatriates, largely from Arab and South and East Asian countries(7). The study was conducted in Hamad General Hospital in the capital city Doha, which caters for all specialty referrals, including Neurology. This referral center provides, specialized outpatients clinics in Neurology including epileptology, inpatient medical care and specialized neurology, neurosurgery, neuroradiology and neurophysiology services. Then the emergency medical services were free as were the drugs provided for out- and inpatients; even today only nominal charges are made. In the absence of other hospitals providing an inpatient service we believe that the series reported here includes all hospital cases of epilepsy in the country presenting during the study period and consequently the data can be extrapolated as a community-based estimation.
epilepsy
Materials and Methods: Introduction: It is estimated that about 50 million people worldwide suffer from epilepsy. In developed countries the incidence of epilepsy varies between 50 and 100 per 100,000 persons per year. In developing countries the incidence rates are higher due to population demographic characteristics and lower standards of epilepsy care(1'2'3). Fortunately, appropriate therapy with conventional and newer anti-epileptic drugs (AEDs) is effective in preventing or reducing the frequency of seizures in most cases of epilepsy but in approximately 20% of epileptic patients sei-
Address for correspondence: Dr. Hassan J. Al Hail, MBBS, Facharzt Neurology Section, Department Medicine Hamad Medical Corporation, P. O. Box 3050, Doha, Qatar Fax: (+974) 4422773; E-mail:
[email protected]
With the aim of using this retrospective hospital-based study to determine indirectly the incidence of epilepsy and causes of IE in Qatar, the records were reviewed of all patients with epilepsy 13 years of age and above admitted to Hamad General Hospital in the period from January 1992 to December 2000. Data on demographic characteristics, seizure semiology, physical examination, AED medication, compliance to treatment and underlying causes were collected. All patients had undergone complete blood cell count, routine blood chemistry, AED plasma levels, scalp electroencephalography (EEG) and brain computer tomography (CT) or magnetic resonance imaging (MRI). Those patients who were undertreated or showed poor compliance to treatment by definition were not regarded as IE. Definitions for the classification of etiology and semiology were adopted from the International League Against Epilepsy guidelines for epidemiologic studies on epilepsy(8). Patients with
11
Epidemiology and Etiology of Intractable Epilepsy in Qatar
IE (I.C.D. code no. 345.0.1) were identified for more detailed analysis. IE was defined for this study as occurrence of two or more seizure episodes per month despite adequate mono- or poly-therapy of AED medication for at least two years. The incidence of epilepsy in Qatar was based on an estimate of the number of new epileptic patients seen at the hospital emergency department, inpatient admission and outpatient clinics over the period 1st January 1992 to 31st December 2000. An incidence rate with confidence intervals (CI) was calculated for each study group.
Results: Intractable epilepsy Over the eight years, 219 patients were admitted to the hospital with uncontrolled epilepsy. Their mean age was 21.4 + 17.3 (range 13-48) years. Fifty-one (23%) were Qatari and 168 (77%) were expatriates. The M:F ratio was 2:1. The mean ages were 31.1+17.4 (range 13- 45) and 30.2 +16.7 (13-48) years in Qatari patients and in expatriates respectively. The incidence rate of hospital admission with uncontrolled epilepsy was calculated as 25 per 100,000 persons (95% CI 23-27). Of the 219 patients admitted with uncontrolled epilepsy 39 (18%) fulfilled the criteria for IE. The incidence of IE was calculated as 4.5 per 100,000 persons (95% CI 4.2-5.7). In the native Qatari population the incidence of IE was 1 in 100,000 persons per year and in expatriates it was 3.5 per 100000 persons per year. The CI for these two groups could not be calculated because separate figures for Qataris and expatriates in the census were not released. The most common type of IE was idiopathic generalized epilepsy, which was encountered in 29 patients (75%). Eight patients (19%) had symptomatic epilepsy, five of them had a stroke and three had a head injury. Two patients (6%) had temporal lobe epilepsy.
Al Hail H., et. al.
the incidence estimates for our population. The crude annual incidence rate of 174 in 100,000 is comparable with incidence rates in developing countries but is higher 9,10) . This is than those found in developed countries (Table 7/ explained by the demographic characteristics in Qatar and other developing countries where the proportion of a younger population is high. In contrast to many developing countries, in the Gulf region there is a large population of young people as part of the expatriate work force. Moreover, we have included in our series patients who were younger (13 years) than those in most studies on western populations. As far as we know incidence studies for the Gulf region have not been reported but Al Rajeh et al in a community-based study(11) showed a prevalence rate of 645 per 100,000 in Saudi Arabia. The prevalence rate of epilepsy in India has been reported as 559 per 100,000(12). Table 1: Annual incidence rate of epilepsy per 100,000 persons in population-based studies from some developing and developed countries. Country
Reference
China
Li et al (15)
Ecuador England Ethiopia
Year
Placencia et al
(3)
Cockerell et al
(16)
Tekle-Haimanot et al
(17)
(18)
This study provided for the first time estimates on the incidence of epilepsy and IE in Qatar. Usually community-based studies provide the best estimate of epilepsy incidence but the uniqueness of the health care system in our small peninsular state and the presence of a single referral center, in our opinion, justify these figures being considered as an approximation of
12
60
35
1992
137
190
1996
06
23
1997
139
64
Loiseau
1990
271
24
Guam
Stanhope et al (19)
1972
30
35
Italy
Granieri et al (20)
1983
230
33
Qatar
Present study
174
Sweden*
Tanzania USA
Discussion:
1985
France
2001
1217
Forsgren et al
(21)
1990
107
34
Forsgren et al
(8)
Rwiza et al
1996
160
56
(22+)
1992
122
73
(10)
1993
880
44
Hauser et al
Incidence of epilepsy in Qatar During the calendar year 2001 a total of 1217 new epileptic patients were seen at this referral center. Eight hundred and seven were male and 410 female, male to female ratio (M:F) of 2:1 with ages ranging from 13 to 85 years. From these data the incidence of epilepsy in the above mentioned population was estimated as 174 in 100,000 persons per year.
No. of Incidence patients
* age > 17 years
Determining a proper diagnosis of epilepsy in general has a great implication on treatment decision and prognostic anticipation. The diagnosis should involve the type of seizure plus the cause and the epileptic syndrome. On the other hand critical diagnostic evaluation has to be established to rule out poor compliance to treatment and non-epileptic conditions mimicking seizures (e.g. migraine, syncope, pseudoseizure) to avoid erroneous labeling of intractability of seizure(13). We made every effort to determine the underling cause of seizures in our series by scrutinizing seizure semiology and reviewing EEG and imaging examinations. The high incidence of idiopathic epilepsy (75%) among our patients is probably an
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Epidemiology and Etiology of Intractable Epilepsy in Qatar
over estimation and an indication of shortage of more elaborate investigative procedures. Studies have shown that secondary epilepsy with specific etiology reaches up to 85%. Use of diagnostic tools like video monitoring, ambulatory EEG and more invasive studies (e.g. sphenoidal, trans-zygomatic and depth electrodes), increase the chances for picking up secondary epilepsy and localizing the focus. The results of our hospital-based study highly estimated the incidence of epilepsy in Qatar although the incidence of IE is
Al Hail H., et. al.
probably underestimated in Qatar and in most developing countries because of the unavailability of adequate epilepsy diagnostic and monitoring technology. Introducing such facilities and establishing a specialized epilepsy center would offer our IE patients more powerful treatment options such as epilepsy surgery and vagus nerve stimulation. Although such undertakings sound unrealistic in developing countries, the cost of epilepsy care without surgery may be higher (14) .
References: 1. Hopkins A, Shorvon SD. Definition and epidemiology of epilepsy. In: eds. Hopkins A, Shorvon SD, Caseino C, eds. Epilepsy. 2nd edition. London: Chapman and Hall, 1995; 1-24. 2. Shorvon SD. Epidemiology, classification, natural history, and genetics of epilepsy. Lancet 1990; 336: 93-106. 3. Placencia M, Shorvon D, Paredes V. Epileptic seizures in an Andean region of Ecuador. Brain 1990: 115: 771-782. 4. Caseino GD. Intractable partial epilepsy; evaluation and treatment. Mayo clin proc 1990; 65:1578-1586. 5. Sander JWAS. Some aspects of prognosis in the epilepsies: Future directions. Epilepsia 1993; 34: 1007-1016. 6. Murray MI, Halpern MT, Leppik IE. Cost of refractory epilepsy in adults in the USA. Epilepsy Res 1996; 23: 139-148. 7. Qatar Population Census - March 1986 and Marchl997. 8. Commission on epidemiology and prognosis. International League Against Epilepsy. Guidelines for Epidemiologic studies on epilepsy. Epilepsia 1993; 34: 592-596. 9. Forsgren L, Bucht G, Eriksson S, Bergmark L. Incidence and clinical characterization of unprovoked seizures in adults: A prospective population-based study. Epilepsia 1996; 37:224-229. 10. Hauser WA, Hesdorjfer DC. Epilepsy, causes and consequences. New York: Demos, 1990. 11. Al Rajeh S, Awada A, Bademosi O, Ogunniyi A. The prevalence of epilepsy and other seizure disorders in an Arab population: A community-based study. Seizure 2001; 10: 410-4. 12. Bharucha NE. Epidemiology of epilepsy in India. Epilepsia 2003; 44 (supp I): 9-11.
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13. Smith D, Defalla BA, Chadwick DW. The misdiagnosis of epilepsy and management of refractory Epilepsy in a specialist clinic. QJM1999; 92:15-23. 14. Lesser RR. The role of epilepsy center in delivering care to patients with intractable epilepsy. Neurology 1994; 44: 1347-1352. 15. Li S, Schoenberg BS, Wang C, Cheng X, Zhou S, Bolz C. Epidemiology of epilepsy in urban areas of the Peoples Republic of China. Epilepsia . 1985; 26: 391-394 16. Cockerell OC, Goodridge DMG, Brodie D, Sander JWAS, Shorvon SD. Neurological disease in a defined population: The results of a pilot study in two general practices. Neuro epidemiology 1996; 15: 73-82. 17. Tickle-Haimanot R, Forsgren L, Ekstedt J. Incidence of epilepsy in rural central Ethiopia. Epilepsia 1997; 38:541-546. 18. Loiseau J, Loiseau P, Guyot M, Duche' MD, Dartiques J-F, Aubler B. Survey of seizure disorder in the French southwest. Incidence of epileptic syndromes. Epilepsia 1990; 31: 391-396. 19. Stanhope JM, Brody J A, Brink E. Convulsions among Chamorro people of Guam, Mariana Island. 1. Seizure disorders. Am J Epidemiol 1972; 95: 292-298. 20. Granieri E, Rosati G, Tola R. A descriptive study of epilepsy in the district of Copporo, Italy, 1964-1978. Epilepsia 1983; 24: 502-514 21. Forsgren L. Prospective incidence study and clinical characterization in seizures in newly referred adults. Epilepsia 1990; 31: 292-301. 22. Rwiza HT, Kilonzo GP, Haule J. Prevalence and incidence of epilepsy in Ulanga, a rural Tanzanian district: a communitybased study. Epilepsia 1992; 33: 1051-1056.
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