Introduction: Third Wave

LIFE2YEARS1066 builds on the foundations of longitudinal population based studies conducted by the 10/66 Dementia Research Group in 2004-6 (baseline) and 2007-9 (incidence wave) (20). The current project adds a third wave of data collection, in the same catchment areas. We will first enumerate the catchment areas again to identify all those currently aged 65 years and over (prevalence sample). This will include:

a) those surviving from the original surveys, and still living in the area (these will by now be aged 75 years or over)
b) those who have aged to 65 years since baseline (2004-6)
c) those aged 65 years or over who had migrated into the area since baseline

We shall also identify an incidence sample comprising all those who were interviewed in our baseline sample and are still alive and available for re-interview. This will clearly overlap considerably with the prevalence sample, but will also include baseline interviewees who have moved out of the catchment area but remain accessible. The purpose of the incidence sample is to continue our study of the aetiology of dementia over a full 10-year follow-up period from the original baseline interviews.

The survey assessment in the third wave will be the same for all participants (see below). Blood samples will be sought from all participants for the purposes of DNA genotyping, haematological and biochemical analyses. To develop the primary care risk assessment tool, a nested cohort of those with no current needs for care (in each country, 150 individuals from the prevalence sample identified at high risk and 150 at low risk of developing dependence, total cohort n = 2,100) will be invited to consent for a briefer reassessment 18 month after baseline to ascertain changes in health, disability and incidence of needs for care. Additional (more costly) assays will be carried out on the stored blood samples for these individuals.The project is well known in the communities where we work. We shall carry out a further round of community
consultation and sensitisation prior to the third wave. The trained doorknockers will take into the field a copy of the baseline register trimmed of the names of all those known to have died or moved away, they will seek to locate the individuals, while also knocking at all doors to identify all others who may be eligible for the third wave of the survey. When potential eligible participants are identified, information sheets describing the new phase of the project will be given to those concerned and a further visit to seek informed consent arranged.

Objectives

• To assess long-term trends in the prevalence, determinants, and impacts of chronic disease in rapidly developing, and ageing populations in Latin America, China and India.
• To model outcomes of direct relevance to policymakers the average expectancy of years spent in a state of disability or dependence, comparing estimates between sites, and within sites over time
• To seek to explain observed differences in health expectancy between study sites, and to identify potentially modifiable determinants of health expectancy (particularly indicators of frailty).
• To address acknowledged limitations of previous research into frailty by:
• using, where possible objective clinical assessments and laboratory biomarkers of age related decline in specific organ based and physiological systems.
• taking a multidimensional approach, exploring the role of individual frailty dimensions, and interactions between them, using factor and multiple correspondence analysis to develop more informative measurement models based on latent traits/ clusters, informed by theoretical principles
• To develop and validate a simple practice-based multidimensional risk assessment tool to identify older people at risk of functional decline and onset of care dependence
• To complete a final 10/66 incidence wave, studying the longer-term effect of cardiovascular and other potential risk factors assessed at baseline (2004-2006)

Data collection

LIFE2YEARS1066 household interviews follow the protocol developed, validated and used successfully in the previous two waves (for which approval was granted by KREC). The questionnaire is founded on that used in the baseline wave (to fulfil our aim of making valid comparisons across the 10-year interval). Data collection comprises five elements, all conducted at the participant’s own home (or at another private location, for example a clinical centre, if they prefer).

1. A brief household interview with a key informant, outlining the household composition, household assets, and household food consumption (20 minutes).

2. Participant interview: comprising three elements:

• A background sociodemographic, health and lifestyles questionnaire (30 minutes)
• A cognitive test battery (20 minutes)
• A structured mental state clinical interview (15-40minutes). The background interview is administered to a proxy informant if the participant lacks capacity to respond.

3. Participant structured neurological and physical examination (50 minutes), including pulse, blood pressure, anthropometry, physical frailty assessments, spirometry and vision and hearing tests.

4. Informant interview (20-50 minutes): A key informant, usually a co-resident family member, provides structured information on any changes in the participant’s intellectual and functional status, and helps the interviewer quantify care needs. If involved in caring, the informant reports care arrangements and carer strain.

5. A 20 ml fasting blood sample will be requested from all participants. This will be obtained first thing in the morning, on a separate occasion, after the survey data has been collected.

Study resources for the 10/66 Life2Years study can be found here.

Funding

This project (henceforth referred to as LIFE2YEARS1066) has been funded by the European Research Council (ERC) to carry out a third wave of population based surveys in established study catchment areas in Cuba, Dominican Republic, Puerto Rico, Venezuela, Mexico, Peru, and China (see https://erc.europa.eu/projects-figures/erc-funded-projects)

References

20. Prince M, Ferri CP, Acosta D, Albanese E, Arizaga R, Dewey M, Gavrilova SI, Guerra M, Huang Y, Jacob KS, et al. The protocols for the 10/66 Dementia Research Group population-based research programme. BMC Public Health. 2007 Jul;7(1):165.

21. Sullivan DF. A single index of mortality and morbidity. HSMHA Health Rep. 1971 Apr;86(4):34754.