Acta Neurol Scand 2015: 132: 203–211 DOI: 10.1111/ane.12384
© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd ACTA NEUROLOGICA SCANDINAVICA
Epidemiology of epilepsy and its burden in Kolkata, India Banerjee TK, Dutta S, Ray BK, Ghosal M, Hazra A, Chaudhuri A, Das SK. Epidemiology of epilepsy and its burden in Kolkata, India. Acta Neurol Scand 2015: 132: 203–211. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. Background – Disability-adjusted life year (DALY) is a time-based measure of disease burden incorporating both disability and mortality. Our study aimed to determine the DALY lost from epilepsy in an Indian metropolis. Methods – A population-based prospective study on epilepsy was conducted over 5 years (2003–8) in Kolkata, India, on randomly selected 100,802 subjects (males 53,209, females 47,593) to assess prevalence as well as to capture incident cases of epilepsy and those incident cases that died. Standard case definitions were used. The data were used to estimate years of life lost (YLL) due to premature mortality, years of life lived with disability (YLD), and DALY, utilizing the prevalence-based Global Burden of Disease (GBD) 2010 approach. Age- and gender-specific figures were computed. Results – During 2003–2004, a total of 476 subjects with active epilepsy were detected and the age-adjusted prevalence rate was 4.71 per 1000. Over 5 years, there were 197 incident cases of epilepsy of whom 26 died. The age-adjusted annual incidence rate of epilepsy was 38.3 per 100,000. The all-cause standardized mortality rate (SMR) of epilepsy was 2.4. The burden of epilepsy in the year 2007–8 revealed the overall YLL was 755 per 100,000, and the overall YLD ranged from 14.45 to 31.0 per 100,000 persons depending on the clinical severity of the epilepsy. Both YLL and YLD values were higher in males than in females. The overall DALY lost due to epilepsy in 2007–8 was found to be 846.96 (males 1183.04, females 463.81) per 100,000. Conclusions – This is the first study in India to determine the DALY of epilepsy using GBD 2010. The results reveal a substantial burden of epilepsy in our setting. Similar such studies are needed in other parts of India in both urban and rural settings.
Introduction
Prevalence, incidence, and mortality are necessary to express burden of illness (BOI). However, these parameters alone do not fully reflect the BOI in non-communicable diseases which are characterized by low mortality and chronic disability. In 1992, a metric termed ‘disabilityadjusted life years (DALYs)’ was introduced. It incorporates both mortality and disability and is considered to be appropriate to express BOI in a wide range of chronic ailments (1). Mental and neurological illnesses accounted for 12.5% of the total DALYs lost in the year 2000, taking all diseases and injuries into consideration.
T. K. Banerjee1, S. Dutta2, B. K. Ray3, M. Ghosal4, A. Hazra5, A. Chaudhuri6, S. K. Das3 1 Department of Neurology, National Neuroscience Centre, Kolkata, India; 2Department of Statistics, Ballygunje Science College, University of Calcutta, Kolkata, India; 3Department of Neurology, BIN and IPGME&R, Kolkata, India; 4Department of Psychiatry, Medical College Kolkata, Kolkata, India; 5Department of Pharmacology, IPGME&R, Kolkata, India; 6Sampling Unit, Indian Statistical Institute, Kolkata, India
Key words: epilepsy; disability-adjusted life years (DALYs); prevalence; incidence; treatment gap; India; mortality S. K. Das, Department of Neurology, Burdwan Medical college, Dist. Burdwan, West Bengal 713104, India Tel.: 91-33-2223-0003 Fax: +91 33 24751799 e-mail: [email protected] Work done at: Bangur Institute of Neurosciences (BIN) and Institute of Postgraduate Medical Education & Research (IPGME&R), Kolkata, India. Accepted for publication January 16, 2015
This will presumably increase to 15% by the year 2020 (2). Epilepsy is one of the leading neurological diseases. According to the Global Burden of Disease (GBD) 2010 study, epilepsy accounted for 253 DALYs per 100,000 people globally, which amounts to 0.75% of the total GBD (3). Furthermore, over 80% of individuals with epilepsy live in developing countries, where disease is largely untreated (4). In India, more than 10 million persons suffer from epilepsy. Overall age-adjusted prevalence per 1000 was estimated as 5.59 (95% C.I. 4.15–7.03) (5). Our longitudinal study in city of Kolkata demonstrated that the incidence rate and the standardized mortality rates (SMRs) of 203
Banerjee et al. epilepsy were 27.27 per 100,000 person-year and 2.58, respectively (6). The magnitude of epilepsy treatment gap (i.e., percentage of people with untreated epilepsy) in India ranges from 22% in urban settings to as high as 90% in villages (7). Hence, in developing countries like India, where there is a substantial burden of untreated epilepsy, DALY is expected to be high. The aim of this study was to determine prevalence, incidence, and mortality profiles of epilepsy in the city of Kolkata, India. Besides, we also determined the BOI of epilepsy in our city using prevalence-based approach to compute DALYs, like the one utilized in GBD 2010 study. Materials and methods
A population-based longitudinal survey on epilepsy was conducted in Kolkata, the eastern metropolis of India, from March 2003 through February 2008. The city has an overall literacy rate of 81.31% (males 84.07% and females 79.9%). The demographic structure comprises 10% between 0 and 6 years and 7% above the age of 60 years with overall male: female ratio 1.1. Economically, the population predominantly belongs to middle-income group. The survey was conducted on a stratified, randomly selected sample of 100,802 subjects (53,209 men, 47,593 women). Municipal area of city of Kolkata comprises 5200 smaller units known as National Sample Survey Organization (NSSO) blocks, with an average of 75–150 households in each block. For the purpose of our study, we divided city into six sampling strata. Stratum I comprised predominantly slum areas in different parts of city. Remaining strata II to VI covered different geographical areas (northern, southern, and central) of the city—two strata each were from the northern and southern parts (one with preponderance of high-rise building complexes and other without) and one from central part with predominant high-rise buildings. From each stratum, multiple NSSO blocks (number proportionate to the population) were randomly selected. In each selected block, alternate houses were surveyed. A total of 100,802 subjects thus recruited were surveyed annually for 5 years from 2003 to 2008 to capture incident cases of epilepsy. The attrition of study population, through migration or non-availability otherwise, was minimal (
© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd ACTA NEUROLOGICA SCANDINAVICA
Epidemiology of epilepsy and its burden in Kolkata, India Banerjee TK, Dutta S, Ray BK, Ghosal M, Hazra A, Chaudhuri A, Das SK. Epidemiology of epilepsy and its burden in Kolkata, India. Acta Neurol Scand 2015: 132: 203–211. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. Background – Disability-adjusted life year (DALY) is a time-based measure of disease burden incorporating both disability and mortality. Our study aimed to determine the DALY lost from epilepsy in an Indian metropolis. Methods – A population-based prospective study on epilepsy was conducted over 5 years (2003–8) in Kolkata, India, on randomly selected 100,802 subjects (males 53,209, females 47,593) to assess prevalence as well as to capture incident cases of epilepsy and those incident cases that died. Standard case definitions were used. The data were used to estimate years of life lost (YLL) due to premature mortality, years of life lived with disability (YLD), and DALY, utilizing the prevalence-based Global Burden of Disease (GBD) 2010 approach. Age- and gender-specific figures were computed. Results – During 2003–2004, a total of 476 subjects with active epilepsy were detected and the age-adjusted prevalence rate was 4.71 per 1000. Over 5 years, there were 197 incident cases of epilepsy of whom 26 died. The age-adjusted annual incidence rate of epilepsy was 38.3 per 100,000. The all-cause standardized mortality rate (SMR) of epilepsy was 2.4. The burden of epilepsy in the year 2007–8 revealed the overall YLL was 755 per 100,000, and the overall YLD ranged from 14.45 to 31.0 per 100,000 persons depending on the clinical severity of the epilepsy. Both YLL and YLD values were higher in males than in females. The overall DALY lost due to epilepsy in 2007–8 was found to be 846.96 (males 1183.04, females 463.81) per 100,000. Conclusions – This is the first study in India to determine the DALY of epilepsy using GBD 2010. The results reveal a substantial burden of epilepsy in our setting. Similar such studies are needed in other parts of India in both urban and rural settings.
Introduction
Prevalence, incidence, and mortality are necessary to express burden of illness (BOI). However, these parameters alone do not fully reflect the BOI in non-communicable diseases which are characterized by low mortality and chronic disability. In 1992, a metric termed ‘disabilityadjusted life years (DALYs)’ was introduced. It incorporates both mortality and disability and is considered to be appropriate to express BOI in a wide range of chronic ailments (1). Mental and neurological illnesses accounted for 12.5% of the total DALYs lost in the year 2000, taking all diseases and injuries into consideration.
T. K. Banerjee1, S. Dutta2, B. K. Ray3, M. Ghosal4, A. Hazra5, A. Chaudhuri6, S. K. Das3 1 Department of Neurology, National Neuroscience Centre, Kolkata, India; 2Department of Statistics, Ballygunje Science College, University of Calcutta, Kolkata, India; 3Department of Neurology, BIN and IPGME&R, Kolkata, India; 4Department of Psychiatry, Medical College Kolkata, Kolkata, India; 5Department of Pharmacology, IPGME&R, Kolkata, India; 6Sampling Unit, Indian Statistical Institute, Kolkata, India
Key words: epilepsy; disability-adjusted life years (DALYs); prevalence; incidence; treatment gap; India; mortality S. K. Das, Department of Neurology, Burdwan Medical college, Dist. Burdwan, West Bengal 713104, India Tel.: 91-33-2223-0003 Fax: +91 33 24751799 e-mail: [email protected] Work done at: Bangur Institute of Neurosciences (BIN) and Institute of Postgraduate Medical Education & Research (IPGME&R), Kolkata, India. Accepted for publication January 16, 2015
This will presumably increase to 15% by the year 2020 (2). Epilepsy is one of the leading neurological diseases. According to the Global Burden of Disease (GBD) 2010 study, epilepsy accounted for 253 DALYs per 100,000 people globally, which amounts to 0.75% of the total GBD (3). Furthermore, over 80% of individuals with epilepsy live in developing countries, where disease is largely untreated (4). In India, more than 10 million persons suffer from epilepsy. Overall age-adjusted prevalence per 1000 was estimated as 5.59 (95% C.I. 4.15–7.03) (5). Our longitudinal study in city of Kolkata demonstrated that the incidence rate and the standardized mortality rates (SMRs) of 203
Banerjee et al. epilepsy were 27.27 per 100,000 person-year and 2.58, respectively (6). The magnitude of epilepsy treatment gap (i.e., percentage of people with untreated epilepsy) in India ranges from 22% in urban settings to as high as 90% in villages (7). Hence, in developing countries like India, where there is a substantial burden of untreated epilepsy, DALY is expected to be high. The aim of this study was to determine prevalence, incidence, and mortality profiles of epilepsy in the city of Kolkata, India. Besides, we also determined the BOI of epilepsy in our city using prevalence-based approach to compute DALYs, like the one utilized in GBD 2010 study. Materials and methods
A population-based longitudinal survey on epilepsy was conducted in Kolkata, the eastern metropolis of India, from March 2003 through February 2008. The city has an overall literacy rate of 81.31% (males 84.07% and females 79.9%). The demographic structure comprises 10% between 0 and 6 years and 7% above the age of 60 years with overall male: female ratio 1.1. Economically, the population predominantly belongs to middle-income group. The survey was conducted on a stratified, randomly selected sample of 100,802 subjects (53,209 men, 47,593 women). Municipal area of city of Kolkata comprises 5200 smaller units known as National Sample Survey Organization (NSSO) blocks, with an average of 75–150 households in each block. For the purpose of our study, we divided city into six sampling strata. Stratum I comprised predominantly slum areas in different parts of city. Remaining strata II to VI covered different geographical areas (northern, southern, and central) of the city—two strata each were from the northern and southern parts (one with preponderance of high-rise building complexes and other without) and one from central part with predominant high-rise buildings. From each stratum, multiple NSSO blocks (number proportionate to the population) were randomly selected. In each selected block, alternate houses were surveyed. A total of 100,802 subjects thus recruited were surveyed annually for 5 years from 2003 to 2008 to capture incident cases of epilepsy. The attrition of study population, through migration or non-availability otherwise, was minimal (
