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

We report the findings of a total population survey of Thugbah communi ty 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 9 8%, specificity 89%) administered at a face-to-face interview. Individ uals with abnormal responses were then evaluated by a neurologist usin g specific guidelines and defined diagnostic criteria to document neur ological disease. The questionnaire was readministered blind by a neur ologist to all those with abnormal responses and a 1-in-20 random samp le of those without abnormal responses, respectively. The family membe rs of an individual with an abnormal response were also screened to im prove accuracy. A total of 23,227 Saudis (98% of the eligible subjects ) were screened and those residing in Thugbah on the reference date (2 2,630) were used to calculate the point prevalence rates. Forty-two pe rcent 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 fir st cousins were present in 54.6%. The demographic characteristics of T hugbah community were similar to those in other parts of SA. The overa ll crude prevalence ratio (PR) for all forms of neurological disease w as 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 mor e frequent than febrile convulsions (0.84). Mental retardation, cerebr al palsy syndrome, and microcephaly were common pediatric problems wit h PRs of 6.27, 5.30 and 1.99, respectively. Stroke, Parkinson's diseas e, 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 a s hydrocephalus and meningomyelocele were more prevalent than spinal m uscular atrophy (0.13), congenital brachial palsy (O.13) and narcoleps y (0.04). Multiple sclerosis was rare (0.04). Osteoarthritis and low b ack pain syndromes were the main non-neurological conditions seen. The major medical diseases that may be neurologically relevant were diabe tes mellitus, hypertension, and connective tissue disorders. The compl eteness of the study coverage and data accuracy suggest that our resul ts most likely reflect the true community prevalence of these neurolog ical disorders in Thugbah community. The similarity between the demogr aphic characteristics of Thugbah and other parts of SA suggest that th e findings may be generalizable for all of SA. However, when comparing our results with other communities, age and sex adjustment would be n eeded and differences in consanguinity rates should also be considered . The availability of health care facilities in other communities woul d similarly affect the ability to recognize neurological diseases.