Prevalence of essential tremor in the city of Kolkata, India: a house-to-house survey

Background and purpose:  Prevalence of essential tremor (ET), one of the most common movement disorders, has not been properly evaluated amongst heterogeneous population in India.
Methods:  We conducted a cross-sectional epidemiological study on the prevalence of ET in a randomly stratified population in the metropolitan city of Kolkata (erstwhile Calcutta), India, by a field team headed by a specialist doctor. A two-stage house-to-house survey was carried out with a validated screening instrument.
Results:  A population of 52377 was screened and a total of 184 cases of ET were identified as per pre-defined criteria and the prevalence rate adjusted to World Standard Population was 3.95 per 1000 (95% CI: 3.40–4.56). Age-specific prevalence showed increasing prevalence with aging. Sex-specific prevalence did not show significant difference between men and women. Socio-economic factors appeared to influence the prevalence and risk of ET was higher amongst slum dwellers versus non-slum population (odd ratio-2.29). Family history was positive in about one-fifth of the cases.
Conclusion:  This study has documented that the prevalence of ET above 40 years in India is similar to that of many countries globally and common amongst slum dwellers and there are fewer familial cases.