Cohort profile: The Chilean National Health Examination Survey (Encuesta Nacional de Salud, Chile ENS)

Authors: Margozzini P.(1), Passi-Solar A.(1,2), Scholes S.(2), Valdivia G.(1), Ferreccio C. (1), Bedregal P., Cerda J., Torres M., Cortes S., Vives A., Errázuriz A., Villarroel L., Viviani P., Padilla O., Domínguez A., Quiroga T., Solari S., Bambs C., Sapag J., ENSCC and Mindell JS(2)

  1. Department of Public Health, Faculty of Medicine, Pontificia Universidad de Chile, Santiago, Chile.
  2. Health and Social Surveys Research Group, Research Department of Epidemiology & Public Health, UCL (University College London), London, UK
  3. Ministerio de Salud de Chile, División de Planificación Sanitaria, subsecretaría de Salud Pública, Santiago, Chile. Working group: ENS Clinical Collaborators (ENSCC)

Laboratory and fieldwork: TM Srta. Jacqueline Parada, TM Sr. Cesar González, TM Sr. Rodrigo Maulén, Sra. Mónica Rebolledo Alberto Maiz, Arturo Borzutzky, Attilio Rigotti, Catalina Dussaillant, Cynthia Cantarutti, Eugenio Arteaga, Eugenio Maul, Felipe Quezada, Fernando Poblete Gilberto González, Guadalupe Echeverría, Hector Jorquera, Javiera Martinez, Joaquin Montero, Josefina Duran, J Rozowski, Juan Fco. Miquel, Juan José Trebilcock, Julia Santin, Lorena Mosso, Luis Rizzi l Manuel Espinoza, Marcela Carrasco, Marco Arrese, María Elvira BALCELLS, Matias Winter, Mauricio Cuello, Monica Acevedo, Patricio Smith, Paulina Villaseca, PedroP Marin, Ricardo Olea, Rodrigo Santis, Rodrigo Tagle,Veronica Irribarra, Claudia Veliz, David Jofré, Dr. Torres, Felipe Bellolio, Fernando Saldías , Loreto Massardo, Marcela Aracena, Marcela Ferres, Nicolas Velasco, Sergio Jacobelli, Ximena Veliz, Gloria Valdés, Carolina del Valle, Pedro Zitko

Keywords: Chile; Health examination survey; General population; Cross-sectional surveys

Acknowledgement: Diretores DIPLAS desde claudia gonzales hasta Jonahan acevedo Martorell Solana Terraza Crustian herrera Claudia Gonzales Ximena Aguilera Fabiola , Dario

First study Ximena Berrios Funding

Why was the cohort set up?

Who is in the cohort?

How often have they been followed up?

What has been measured?

What has it found?

What are the main strengths and weaknesses?

Can I get hold of the data? Where can I find out more?

Why was the ENS cohort set up?

The health reform process that Chile began in 2000 required an updated baseline and continuous health diagnosis to evaluate health objectives, reformulating health priorities and planning, which motivated the improvement of national health monitoring of NCDs.ref objetivos sanitarios. Since 2000, MINSAL started to work efforts to obtain national information on chronic non-communicable diseases and their determinants through population surveys, under the framework of a progressive method, first introducing the application of health interview surveys with health behaviours and quality of life measurements (National Quality Survey of Life and Health, ENCAVI)ref and later complementing them with more objective measures introducing a National Health and Examination Survey (ENS).

The Encuesta Nacional de Salud de Chile (ENS, National health survey) is a series of three cross-sectional health examination surveys (2003, 2009/10 and 2016/17) covering the adult general population from Chile. In the last decade, MINSAL has been pushing improvements in the health statistics linkage process which have made it possible for the DEIS (Dirección de Estadísticas e Información de Salud). Chile has a unique identification number. National Data linkage to hospital discharges and mortality registries has permitted these studies to be analysed as cohorts. The purpose of ENS is to estimate the prevalence of chronic non-communicable diseases (NCDs) and risk factors in the adult population. ENS is a national ongoing epidemiological surveillance tool with new independent cross-sectional waves occurring every six years.



Who is in the cohort and how often have they been followed up?

The study designs were similar for the three ENS (2003; 2010; 2017). Each ENS was a nationally representative cross-sectional survey of the free-living general population aged 17 years or older (2003) and aged 15 years or older (2010 and 2017). The study used a multi-stage clustered sampling, with probability-proportional-to-size sampling for the secondary sampling units, so that the probability of selection into the survey sample for each cluster was proportional to its size. Institutionalised, non-Spanish speaking or violent individuals were excluded. Respondents who were pregnant at the time of the survey were also excluded. Persons aged 65 years or over were oversampled. An invitation letter was sent to the selected households, informing them about the survey. Recruitment was face-to-face when the interviewer visited the household to explain about the survey, select the individual within the household, and recruit participation. The interviewer had to visit at least three times, at different times of the day and at least once at the weekend before the household was deemed not contactable. No financial incentives were provided to participants.

First baseline wave of participants was ENS2003. ENS 2003 participants were selected using a stratified random subsample from participants of the Quality of Life and Health Survey 2000.[1] The Quality of Life and Health Survey’s sampling frame was household information from the National Census of 1992, and sampling was carried out by a stratified and cluster design. The subsample of participants for the ENS 2003 was selected using the same age-gender-regional structure of the original sample frame, except for the oversampling of the Bio-Bío Region, where additional funds from PAHO were available to increase the sample size.

Fresh samples were selected for the second and third waves (ENS2010 and ENS2017) surveys based on stratified cluster sampling. Sampling for ENS 2010 and ENS 2017 was based on the master sample frame of the Chilean National Institute of Statistics and the Population and Housing Census of Chile (2002, updated in 2008 for the urban population).

One eligible person was randomly selected for interview within the selected household using a Kish grid (using an automated digital Kish method in 2010 and 2017).[1]

Response rates for the total sample were 63, 75 and 67% in 2003, 2010 and 2017 respectively. As shown in Figure 1, a total of XXX participants aged 15 years or older were added into the dynamic cohort in 2003, 2010 and 2017, respectively (interviewer visit). Of those, X, Y, Z had a second visit with a trained nurse and XYZ gave biological samples for laboratory testing and serum biobank. Cohort outcomes, including hospital discharges and deaths were linked to ENS participants. Currently, hospital discharge and death data are linked and available for ENS years 2003-2010-2017 including data until April 2019. A total of XYZ had at least one hospital discharge and XYZ had died. Until April 2019, the dynamic cohort summed a total of XXX person-years of follow-up. Figure 1: Flow diagram of participants in the ENS Cohort National Health Survey, Chile, 2003–2010-2017

Figure 1: Flow diagram of participants in the National Health Survey, Chile, 2003–2010-2017

ENSnnurselabdeathhosp
13,6193,4523,396743743
25,2934,8844,8284822,616
36,2335,5205,4661182,884

After lab exams: Mental health visit APARTE wat has been measured: Child development visit ***Cohort outcomes

Follow-up is permanent because Chile has a unique identification code that allows for linkage to yearly validated hospital discharge and death datasets with CIE-10 coding.

The response rate to the HSE has fallen in recent years, in com Demographic characteristics of the cohorts Edad genero region zona NEDU ENS 2003-2010-2017

Data are collected by an interviewer visiting the participants in their own homes; measurements are taken in the participants’ own homes by nurses and biological samples by nurses or phlebotomists.

Reason for a lower response rate include the use of an updated household census was updated during

Representativeness of sample Non-response weights so sample is nationally representative of non-institutionalised people aged 17+ Non-response weights so sample is nationally & regionally representative of non-institutionalised people aged 15+ Data collection period Month to month 2003 Oct 2009 to Sept 2010 Month 2016 to month 2017 Data Collected: Dataset production Source data Software Hardware Data type (e.g. secondary data) and Survey type Cross-sectional health examination survey of new, nationally-representative stratified, clustered random sample of the general population.

If there space: For 2009/10 and 2016/17, regions were stratified by rural/urban type area; municipalities were stratified by size. 2003… The sampling stages were municipality (146 selected in 2009/10); area segments (urban blocks of rural census units, 624 in 2009/10); then six households were elected per area segment. All large and middle-sized municipalities were included but only a random sample of the small counties were sampled. There was oversampling of non-Santiago metropolitan and rural areas. but with a double selection probability for people aged 65+. Recruitment: All measures and lab results were posted back to each participant. Participants who were identified as having higher health risk were called and recieved medical counselling by phone. Local health authorities were notified about this group of participans so to check if they have had access to healthcare. Numbers sampled, baseline response rate and successful linkage to hospital discharges and mortality data is shown in Table 1.

First baseline was 2003 Fresh population has been addes with each sucesive wave of the ENS Follow-up is permanent because Chile has a unique identification code that allows for linkage to yearly validated hospital discharge and death datasets with CIE-10 coding. Currently, hospital discharge and death data are linked and available for ENS years 2003-2010-2017 including data until April 2019.

If there space: For 2009/10 and 2016/17, regions were stratified by rural/urban type area; municipalities were stratified by size. 2003… The sampling stages were municipality (146 selected in 2009/10); area segments (urban blocks of rural census units, 624 in 2009/10); then six households were elected per area segment. All large and middle-sized municipalities were included but only a random sample of the small counties were sampled. There was oversampling of non-Santiago metropolitan and rural areas. but with a double selection probability for people aged 65+.

Recruitment:

Numbers sampled, baseline response rate and successful linkage to hospital discharges and mortality data is shown in Table 1.

Reason for a lower response rate include the use of an updated household census

was updated during

Data are collected by an interviewer visiting the participants in their own homes; measurements are taken in the participants’ own homes by nurses and biological samples by nurses or phlebotomists.



Representativeness of sample Non-response weights so sample is nationally representative of non-institutionalised people aged 17+ Non-response weights so sample is nationally & regionally representative of non-institutionalised people aged 15+ Data collection period Month to month 2003 Oct 2009 to Sept 2010 Month 2016 to month 2017 Data Collected: Dataset production Source data Software Hardware

Data type (e.g. secondary data) and Survey type

Cross-sectional health examination survey of new, nationally-representative stratified, clustered random sample of the general population.

Ethical clearance

The ethics committee of the Pontificia Universidad Católica de Chile (PUC) approved the study protocol for this PhD (ID: 200205003, see Appendix A4). The Chilean National Health Survey (ENS) study protocol and ethical consent forms were also approved by the PUC ethics committee and the Chilean Ministry of Health (ENS 2003: number could not be retrieved; 2010: 09-113; 2017: 16-019). Persons selected for inclusion in the Chilean health surveys provided informed and signed consent before participation.

Research ethics approval was obtained from the Ethics Committee of the Chilean Ministry of Health and the Ethics Committee of the Faculty of Medicine, Pontificia Universidad Católica de Chile. All cohort participants provided written informed consent before the baseline survey.



Table 1. Sampling frame, sample size, dates and response rates for the thee national surveys, Encuestas Nacionales de Salud, Chile

variable200320102017
PSU195  146158
Strata13  2930
Region13  1515
Sample3,619  5,4106,233
Nurse visit3,452  4,9895,520
Females1,973  3,2143,918
Aged >=65918  1,0511,517
Death743  507118
Follow-up (y)16.39.12.2
Death (Follow-up max 9y)410  505118


ENS: 2003 2009/10 2016/17

No. of regions? 13 15 15

No. of households selected 5469 7212 9901

Household response rates 63 75 67

Law N°? Samanta

Funding sources The National Health Survey was funded by the Chilean Ministry of Health and carried out by the Department of Public Health, Catholic University of Chile (PUC). We gratefully acknowledge the contribution from… who have made the xxx studies possible.

What is attrition like?

What has been measured?

ENS survey instruments and protocols are described in detail elsewhere.[2]

Similar methods for data collection were used across the three surveys. In the first home visit, a trained interviewer applied health questionnaires face-to-face via computer (CAPI: Computer Assisted Personal Interview), including sociodemogaphics, a list of self-reported medical diagnosis and health-related life-styles and health screening behaviuors (see table X). During the second visit, a trained nurse applied additional questionnaires (e.g. reproductive and sexual health, another set of self-reported medical diagnosis, alcohol consumption and medication intake), biophisiological measures (blood pressure, anthomometric measures)

and recorded the medications participants were currently using (prescribed or not) via a detailed inventory. Medications were classified using the ATC classification system.[3]

Table 1: Content…, Chile ENS2003-2010-2017

Age, gender, marital status Fasting venous blood samples Anthropometric data: measurements of height, weight and waist circumference were taken by trained nurses Biophysical measurements: Blood pressure was measured twice in ENS 2003 and three times in ENS 2009/10 and 2016/17 (using the left arm). Biological samples: Fasting venous blood samples were taken: Serum creatinine was measured in ENS 2009/10 and ENS 2016/17, for calculation of eGFR as a measure of kidney function. No genetic data obtained.

Data linkage The survey can be linked to national mortality and hospital data by request to MinSal. Measures to ensure data quality and anonymisation techniques. Quality assurance ??? Anonymisaion techniques The dataset provided for analysis has had names, addresses and ??? removed . Data Resource Use : Information about data collection Data Resource Access
Applications to access the ENS data Variable formats and naming conventions

What has it found?

Key findings and publications

The ENS constitutes an indispensable source of information for the formulation of health objectives, of the national health strategy for the fulfillment of the health objectives and of the evaluation of its impact. Among others, it is a source of relevant information for: • Studies of disease burden and burden attributable to risk factors. • Contributes to studies of potential demand and cost. • Contributes to the design of national policies and programs for health promotion and prevention (and advocacy). • Contributes to the design and evaluation of coverage of the care system. • It is part of the VENT surveillance system (source of information external to the provider and includes the general population of the entire risk spectrum) • Evaluation of public policies

The ENS not only contributes to Public Health and decision makers, but also contributes to the development of individual clinical medicine in Chile as it provides: • Pre-test probability of the main chronic health problems for the practice of medicine in Chile. • Basis for the formulation and prioritization of clinical competency learning objectives in Chilean universities. • Discussion of normal values ​​of diagnostic tests in the local reality. • Contributes to the evaluation of the population effectiveness of clinical therapies. • It helps to generate in the clinician the knowledge and responsibility of advocacy in favor of health promotion and disease prevention

What are the main strengths and weaknesses of the study?

Strengths and Weaknesses Strengths of the data
The main strengths are the inclusion of health examination data from nationally representative samples of the non-institutionalised general population. The dataset includes variables to adjust for non-response TO DIFFERENT VARIABLES / stages of the survey? and for adjustment for the complex survey design. Limitations of the data Limitations include RESPONSE RATE? and the limited range of data collected. The surveys provide no information on the health of people living in institutions, nor of pregnant women. Over time, topics of interest or thresholds change, so each wave is a compromisebetween continuation of previous measures to provide trend data and updating the measures to provide what is currently needed for surveillance.

Can I get hold of the data? Where can I find out more? The methodology, results and databases of the ENS are freely available to researchers and decision makers through the sector website (http://epi.minsal.cl/encuestas-poblacionales/). Databases with the linkage mortality and hospital discharges are available on request to Minsal (Samanta? mail?) summarise opportunities for data access and collaboration and should include either an email or web address for enquiries or an application form.

Cohort profile in a nutshell

The following sections of the Pocket Profile should be written in complete sentences. Please include all sections and use the sub-headings provided. Aim for about 500 words (including sub-headings) with one simplified flow diagram, figure or table derived or reproduced from the full profile. Pocket Profiles should fill one page of the print version of the IJE, so we may need some flexibility in the final word count.

Cohort profile: The Chilean National Health Examination Survey (Encuesta Nacional de Salud, ENS) Authors: Margozzini P., Passi A., Scholes S., Anriquez S., Mindell JS

Keywords: Chile; Health examination survey; General population; Cross-sectional surveys Corresponding author : Name and email address. Cite this as: The full version of this profile is available at IJE online and should be used when citing this profile • The Chilean ENS series was set up to provide health examination data from a nationally representative sample of the Chilean general population to enable health surveillance and monitoring of health, health risk behaviours, management and extent of diagnosis of key health conditions in the general population and in specific subpopulations to monitor health inequalities. Unique features in Chile are the existence of examination measures not dependent on healthcare data to enable assessment of undiagnosed conditions. • The database was set up DATE and covers the whole of Chile. ENS 2003 covers XXXX individuals in 5469 sampled households; ENS 2009/10 covers XXXX in 7212; and ENS 2016/17 covers XXXX in XXXX. • The data are from three waves of the Chilean Encuestas Nacionales de Salud, national health survey. Each survey was a new, nationally-representative, clustered stratified random sample of individuals within randomly selected households. • The main categories of data collected were demographic, socio-economic, self-reported health, health risk behaviours, diagnosed disease, anthropometry (measured), blood pressure, and blood analytes. • Collaboration and data access… Individual level pseudonymised data can be accessed by request to XXXXXX.

Data Resource Basics: The database covers the whole of Chile. It covers the three health surveys conducted MONTH to MONTH 2003, Oct 2009 to Sep 2010, and MONTH 2016 to MONTH 2017. Each survey selected a new random sample: ENS 2003 covers XXXX individuals in 5469 sampled households; ENS 2009/10 covers XXXX in 7212; and ENS 2016/17 covers XXXX in XXXX. Data Collected:
The data from the three surveys are available for secondary analysis. Data Resource Use:
Reasons to be cautious: The data are representative of the national, non-institutionalised population in Chile; the second and third surveys are also regionally representative. However, people living in institutions, pregnant women, violent people, and those not speaking Spanish were excluded. Collaboration and data access:
Funding and competing interests: Research ethics approval was obtained from the Ethics Committee of the Chilean Ministry of Health and the Ethics Committee of the Faculty of Medicine, Pontificia Universidad Católica de Chile. Each survey was funded by the Chilean Ministry of Health (MinSal). Author affiliations : PM: Department of Public Health, Pontificía Universidad de Chile, Santiago JM, SS, MW: Health and Social Surveys Research Group, Research Department of Epidemiology & Public Health, UCL, London, UK Corresponding author:
Data Collected:

Supplementary Data

Funding

Acknowledgements

Conflict of interest: None declared.

References Spanish language :

Ministerio de Salud, División de Planificación Sanitaria, Departamento de Epidemiología. Encuesta Nacional de Salud ENS Chile 2009–2010. III. Metodologia [National Health Survey ENS Chile 2009–2010. Methodology]. Santiago, Chile: MINSAL; 2010. http://epi.minsal.cl/wp-content/uploads/2016/08/ENS_2009-2010_CAP3_-Metodologi%CC%81a.pdf. Accessed 23rd May 2019

Departamento de Epidemiología. Encuesta Nacional de Salud (ENS). Cuestionarios [National Health Survey. Questionnaires]. Santiago, Chile: Ministerio de Salud, Gobierno de Chile; 2012. http://epi.minsal.cl/cuestionarios-ens/. Accessed 23rd May 2019.

The interview, nurse and laboratory protocols are currently not publicly available, but may be released on request to the Ministry of Health (MINSAL).

Summary information, focussing on ENS 2009/10, is available in English in a paper comparing seven national population health examination surveys: Mindell JS, Moody A, Vecino-Ortiz AI, Alfaro T, Frenz P, Scholes S, et al. Comparison of Health Examination Survey Methods in Brazil, Chile, Colombia, Mexico, England, Scotland, and the United States. Am J Epidemiol. 2017;186:648-658.

Reports of the survey results

Primary data analysis

Ministerio de Salud. Resultados Encuesta de Salud, Chile 2003 [Results of the Health Survey, Chile 2003]. Santiago: MINSAL, 2003.

Ministerio de Salud. Encuesta Nacional de Salud ENS Chile 2009–2010 [National Health Survey ENS 2009–2010]. Santiago: MINSAL, 2010.

Some examples of secondary data analysis

Cabrera S, Alvo M, Mindell JS, Ferro C. La Encuesta Nacional de Salud de Chile entrega información valiosa para planificación de políticas de salud. Análisis de Nefropatía Diabética como indicador de ahorro potencial. [The national health survey for Chile delivers valuable information for planning health policies. Analysis of diabetic nephropathy as an indicator of potential savings.] Revista Medica de Chile.2015;143:679-81.

Cabrera SE, Mindell JS, Toledo M, Alvo M, Ferro CJ. The association between blood pressure and the prevalence of hypertension with geographical latitude and solar radiation: results from the Chilean Health Survey 2009-2010. Am J Epidemiol. 2016;183:1071-3.

Garrido-Méndez A, et al. Association of active commuting with obesity: findings from the Chilean National Health Survey 2009-2010. Rev Med Chil. 2017;145(5):837-44. Doi: 10.4067/s))34-98872017000700837

Lanas F, Seróna P, Muñoza S, Margozzini P, Pui T. Latin American Clinical Epidemiology Network Series – Paper 7: Central obesity measurements better identified risk factors for coronary heart disease risk in the Chilean National Health Survey (2009–2010). J Clin Epidemiol. 2017;86: 111–116. DOI: https://doi.org/10.1016/j.jclinepi.2016.04.01

Markkula N, Zitko P, Peña S, Margozzini P, Retamal P. Prevalence, trends, correlates and treatment of depression in Chile in 2003 to 2010. Soc Psych Psych Epidemiol 2017;52:399-409.

Passi A, Margozzini P, Valenzuela E, Hoyl T, Marín PP, Carrasco M, Olea R, Gac H. Uso inapropiado de medicamentos en adultos mayores: resultados de la Encuesta Nacional de Salud 2010 [Inappropriate medication use among Chilean older people]. Rev Med Chil. 2016;144:417-25. doi: 10.4067/S0034-98872016000400001.

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ALSPAC index offspring profile in a nutshell ALSPAC is a transgenerational prospective observational study investigating influences on health and development across the life course.

Children were recruited from 14 541 baseline pregnancies where mothers resided in and around the City of Bristol, UK, and were due to deliver between 01/04/1991 and 31/12/1992.

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Currently, mortality data are available for HSE years 1994–2008 until the first quarter of 2011 and cancer registrations for these HSE years can be linked from the date of interview.

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words: 2500-3000 up to 5 tables and figures ref 30

Purpose To make the research community aware of the existence of large cohorts around the world. To maximise the use of existing data by fostering collaboration, including sharing data, research questions and methods. Note that:

The IJE does not publish individual cohort studies in its Cohort Profile series. Please submit these as Original Articles. The aim of the Cohort Profile series is to provide up-to-date information about large population-based cohorts with planned long-term data collection. Cohorts with a narrow clinical focus will, in general, not be considered for this series. To warrant publication in the IJE, Cohort Profiles must add substantially to any information about cohorts that is already available on existing websites. Profiles that describe a cohort consortium should focus on the added value of the consortium rather than piecemeal descriptions of the constituent cohorts. Such profiles must include at least one publication based on the collated data from the constituent cohorts to illustrate the added value. At least one of the authors of a Cohort Profile must be a researcher involved with the data resource presented and be available to readers as a contact person. Please identify this author and provide contact details under the section ‘Can I get hold of the data?’

Cohort Profiles will be published online only. They will still be assigned to an IJE issue and listed as ePages in the issue’s Table of Contents.

Format Please refer also to the general Manuscript Preparation instructions.

Title: Begin with ‘Cohort Profile:’ followed by your title (which is usually the name of the cohort) and then any acronym in parentheses.

Author List: (see General instructions).

Note: Cohort Profiles do not require an Abstract. Please enter the ‘Key Features’ (see below) into the Abstract field in the ScholarOne website during submission, and select Not Applicable when asked about Key Messages.

Cohort Profile sub-headings Cohort Profiles MUST use the following sub-headings and address the criteria described under each sub-heading (Cohort Profiles that fail to meet these criteria will not be published):

Key Features

Key features of the Cohort Profile should be provided as bullet points of no more than 200 words in total. Use complete sentences to provide the following information: why the cohort was established and unique feature(s) of the cohort; location, year(s) of baseline data collection; number of participants at baseline; composition of the study population including age range; frequency of follow-up; attrition; number of participants currently in the cohort; main categories of data collected; and collaboration and data access.


    




    

1. Kish L. Survey Sampling. New York: Wiley; 1965. http://doi.wiley.com/10.1002/bimj.19680100122.
2. Ministerio Salud, Chile. [Chilean National Health Survey: Questionnaires, Datasets, and Related Documentation]. 2017. http://epi.minsal.cl/encuesta-ens-descargable/. Accessed 29 Jun 2020.
3. WHO-Collaborating Centre for Drug Statistics Methodology. Guidelines for ATC classification and DDD assignment 2019. 2019. https://www.whocc.no/atc_ddd_index_and_guidelines/guidelines/. Accessed 12 Jul 2021.