Presentation on theme: "Epidemiology of Airway Diseases- Asthma and COPD in India S. K. Jindal Department of Pulmonary Medicine Postgraduate Institute of Medical Education and."— Presentation transcript:
Epidemiology of Airway Diseases- Asthma and COPD in India S. K. Jindal Department of Pulmonary Medicine Postgraduate Institute of Medical Education and Research Chandigarh, India
Prevalence of C.R.D. Global Estimates Ch Resp DisYearPrevalence (Million) Asthma COPD Allergic rhinitis Others2006> 50 S.A.S.> 100 Bousquet et al, ERJ 2007
Global Burden of Asthma Currently: Around 300 m. patients Expected by 2025: 100 m. additional Loss of DALYs: About 15 m./year (around 1% of all DALYs lost) Mortality: Accounts for in every 250 deaths Economic costs: Include direct treatment expenditure and indirect losses due to absenteeism, disability and health-care management.
Global Initiatives in Epidemiology Asthma:ISAAC (International study on Asthma and Allergies in Children) ECRHS (European Community Respiratory Health Survey) COPD:BOLD (Burden of Obstructive Lung Disease) PLATINO (COPD Prevalence in five Latin American Cities)
Global Adult Asthma Prevalence (%) Country Australia N.Zealand Belgium England Germany Spain France U.S. Italy Greece Switzerland Tristan da Cunha Current Ever Recent Wheeze AHR Atopy
Adult* Asthma in Asia Prevalence Rate**(%) China0.67 – 1.39 Hong Kong3.9 – 8.0 Japan3.6 Singapore0.9 – 9.0 South Korea10 – 12.1 Taiwan2.4 – 6.0 Thailand2.91 – 10.1 Range0.67 – 12.1 *>15 year old **Figures reported the collective range of period prevalence of asthma ranging from 3 months to 1 year rates depending on the variation in study methodology Choi et al APSAR 2004
All cause Ranking of Burden of COPD Global Burden of Disease Study Cause of death6 th 3 rd DALYs Worldwide12 th 5 th Developed regions9 th Developing regions4 th Murray & Lopez, Lancet 1997
Prevalence studies on asthma from India Study PopulationAge (yrs) Definition / Methodology Prevalence (%) RegionGroupNo. 1.Viswanathan (1966)North (P)Urban15805All ages Symptoms on interview 1.8 Children 2.Shah (2000)MulticentricSchools Self reported, (ISAAC) Awasthi (2004)North (L)Schools do Mistry (2004)North ( C)Schools Q. wheezing Chakravarthy (2002)South (TN)Field855< 12 Q.Diagnosed asthma 5 6.Chhabra (1998)North (D)Schools Q; Current Paramesh (2002)South (B)Schools Gupta (2001)North (C )Schools IUATLD based validated Q 2.3 Adults 9.Chowgule (1998)West (M)Field ECRHS Q Jindal (2000)North (C )Field > 70Validated Q Aggarwal (2006)MulticentricField73605> 15Validated Q2.4 B = Bangalore; C = Chandigarh; D = Delhi; IUATLD = International Union Against Tuberculosis & Lung Disease; ISAAC = International Study on Allergies and Asthma in Children; L = Lucknow; M = Mumbai; P = Patna; Q = Questionnaire; ECRHS = European Community Respiratory Health Survey; TN = Tamil Nadu
A summary of important field studies from India on prevalence of CB/COPD published in last 30 years AuthorsPopulation group Age (Yrs) Subject No. M F Method of diagnosis Prevalence M F 1Joshi et al (1975)Punjab (Ind) Questionnaire Bhattacharya et al (1975) U.P.(R) Questionnaire Thiruvengadam et al (1977) Madras city (U) Interview Vishwanathan & Singh (1977) Delhi (U) Questionnaire Radha et al (1977)New Delhi (U) Questionnaire & PEF Nigam et al (1982)U.P. (R) Interview Malik SK (1986)Chandigarh (U) Questionnaire & PEF Jindal SK (1993)Punjab (U) Questionnaire & PEF Ray et al (1995)Tamil Nadu (R ) Questionnaire Jindal et al (2006)Multicentric*>= Validated questionnaire PEF = Peak Expiratory Flow; U = Urban; R = Rural; * Bangalore, Chandigarh, Delhi, Kanpur
Variations in prevalence Depend upon differences in: Definition of disease used in the study Study designs Sampling methods Use of study-instruments Collection, recording and analysis of data Interpretation of results Extraneous factors: Expertise & errors True differences: Ethnic, geographical, seasonal, environmental etc.
INSEARCH Study Population (Phase II) Centre RuralUrban Total MaleFemaleMaleFemale Ahmedabad Berhampur Bikaner Chennai Guwahati Kolkata Mumbai Mysore Nagpur Secunderabad Shimla Trivandrum Total
INSEARCH Sampling & Methodology Two stage stratified sampling system –First stage – Village/Urban area (30 clusters per centre) –Second stage – Houses (100 Houses per cluster) All residents of the selected houses aged 15 years were interviewed. Two additional attempts were made to contact an individual in case of non availability at the first visit. A Sample size of subjects was calculated to be required to give a 95% C.I of ±0.3% for a prevalence of 3 %. Questionnaire Administration The Questionnaire was administered by the field staff who were trained for the same. Internal Quality assurance : 10% of the households visited by the study site supervisor randomly. External Quality assurance : Periodic monitoring visits by the officers from the controlling centre ( Chandigarh)
Questionnaire & Definitions Bronchial Symptom Questionnaire (1984) developed by International Union Against Tuberculosis and Lung Diseases (IUALTD). Symptoms in the preceding 12 months were considered Asthma definition Any 1 of: (a) whistling sound from the chest or (b) Early morning chest tightness. AND Any 1 of: (a) attack of asthma. (b) physician diagnosis of asthma in the past or (c) Use of bronchodilators Chronic Bronchitis Definition Cough with expectoration for 3 mths for 2 consecutive years. Objective measurements such as spirometry and bronchial hyper reactivity were not measured. Diagnosis based only on questionnaire.
Statistical analyses 1.Questionnaire pre-testing Test-retest method Split-half method 2.Group comparisons Chi-square test (categorical variables) Students t-test (scalar variable) Univariate and multivariate logistic regression analyses for Odds Ratios (OR) and 95% Confidence Intervals 3.National burden estimates – based on age- standardized prevalence estimates based on Census 2011.
Results: I. Sample 1,69,575 individuals surveyed Urban- 60,764 Rural- 1,08,811 Men – 85,105 Women – 84,470 % of surveyed individuals to the total eligible individuals in the households. Urban – 98.6% Rural – 97.6%
II. National Prevalence (Adults) Asthma- 2.04% Chronic bronchitis (CB)- 3.58% Smoking- Men % Women - 0.5% Any respiratory Symptom - 8.5% Total patient estimates (as per 2011 census): Asthma: million (>15 years) CB: million (>35 years)
Asthma Prevalence in India (INSEARCH) UrbanRural
ETS Exposure in Asthma NoYes ED visits * Hospitalisation Ac. episodes * Parenteral BD6.08.6* Work absence (wks)3.03.6* Steroid use (wks) * BD use (wks) *p < 0.01 (Jindal et al, Chest 1994)
Environmental tobacco smoke exposure and asthma 1.Aggravation and occurrence of increased prevalence of respiratory symptoms 2.Bronchial hyper-responsiveness in adults 3.Aggravation of asthma symptoms 4.Precipitation of acute episodes 5.Risk factor for development of asthma (both children and adults)
Active smoking in asthma in adults 1.Increased bronchial responsiveness 2.Frequent bronchial irritation symptoms 3.Increased sensitization to occupational agents 4.Aggravation of acute episodes 5.Association with asthma severity 6.Risk factor for asthma ? 7.Exaggerated decline in lung functions 8.Role in development of fixed airway obstruction and COPD ?
Health costs on Smoking and COPD 1.Annual cost of management of COPD per patient* Expenditure on smokingRs Direct costs:PatientRs work absenceRs. 410 Indirect lossesRs *Comprised ~ 1/3 of average income of patient ICMR Report, Jindal et al ) 2.Families with one (or more) smoker members had significantly higher health related expenditure, work and school absenteeism and number of illnesses Jindal et al, NMJI 2005
Conclusions The total population prevalence estimate of asthma and CB in adults account for over 32 million patients for the projected 2011 population of around 415 million. Cumulative prevalence increases with age. Smoking, Environmental Tobacco Smoke and Biomass combustion exposures are important & preventable risk factors for asthma as well as CB. Allergic Bronchopulmonary Aspergillosis is a common problem seen in asthma. There is an enormous economic burden from both disorders. Guideline-directed management is significantly cheaper and cost-effective.
Symptom-based diagnosis - Limitations 1.Lack of objective measurements like Spirometry 2.No specific terms for asthma (vs COPD/ CB) in Indian vernacular languages 3.GPs do not often differentiate between asthma and COPD 4.Inhalers and bronchodilators are commonly used/ abused for nonspecific cough/ breathlessness 5.The term asthma is interpreted differently in cross- cultural comparisons (Sunyer et al, AJRCCM 2000) 5. Confounding (bronchiectasis, CB, TB)