A COMMUNITY SURVEY OF NEUROLOGICAL DISORDERS IN SAUDI-ARABIA - THE THUGBAH STUDY

We report the findings of a total population survey of Thugbah community in the Eastern Province of Saudi Arabia (SA) to determine its point prevalence of neuro- logical diseases. During this two-phase door-to-door study, all Saudi nationals living in Thugbah were first screened by trained interviewers using a pretested questionnaire (sensitivity 98%, specificity 89%) administered at a face-to-face interview. Individuals with abnormal responses were then evaluated by a neurologist using specific guidelines and defined diagnostic criteria to document neurological disease. The questionnaire was readministered blind by a neurologist to all those with abnormal responses and a 1-in-20 random sample of those without abnormal responses, respectively. The family members of an individual with an abnormal response were also screened to improve accuracy. A total of 23,227 Saudis (98% of the eligible subjects) were screened and those residing in Thugbah on the reference date (22,630) were used to calculate the point prevalence rates. Forty-two percent of those screened were in the first decade of life and only 1.5% were more than 60 years old. There were marginally more females (50.2%) than males (49.8%). Consanguineous marriages especially between first cousins were present in 54.6%. The demographic characteristics of Thugbah community were similar to those in other parts of SA. The overall crude prevalence ratio (PR) for all forms of neurological disease was 131/1,000 population. All subsequent PRs are per 1,000 population. Headache syndromes were the most prevalent disorder (PR 20.7). The PR for all seizure disorders was 7.60, and the epilepsies (6.54) were more frequent than febrile convulsions (0.84). Mental retardation, cerebral palsy syndrome, and microcephaly were common pediatric problems with PRs of 6.27, 5.30 and 1.99, respectively. Stroke, Parkinson's disease, and Alzheimer's disease were uncommon with respective PRs of 1.8, 0.27 and 0.22. Central nervous system (CNS) malformations (0.49) such as hydrocephalus and meningomyelocele were more prevalent than spinal muscular atrophy (0.13), congenital brachial palsy (O.13) and narcolepsy (0.04). Multiple sclerosis was rare (0.04). Osteoarthritis and low back pain syndromes were the main non-neurological conditions seen. The major medical diseases that may be neurologically relevant were diabetes mellitus, hypertension, and connective tissue disorders. The completeness of the study coverage and data accuracy suggest that our results most likely reflect the true community prevalence of these neurological disorders in Thugbah community. The similarity between the demographic characteristics of Thugbah and other parts of SA suggest that the findings may be generalizable for all of SA. However, when comparing our results with other communities, age and sex adjustment would be needed and differences in consanguinity rates should also be considered. The availability of health care facilities in other communities would similarly affect the ability to recognize neurological diseases.