CNR - Institute of Neuroscience CNR
Institute of Neuroscience
 

Project

Health expectancy indicators: national and international estimates of Disability Free Life Expectancy and Disability Adjusted Life Years

Background

In recent decades life expectancy has increased remarkably in almost all European countries. However, since a longer life does not necessarily mean a healthier life, (the years gained are years in good health or years lived with disability?), several methodological approaches have been developed to study and combine information on life expectancy and disability.

National estimates of the health expectancy indicators may be used to guide health sectors in setting regional/local priorities. But, when comparison across countries is needed, the use of different definitions and instruments for measuring disability might imply that observed differences do not necessarily reflect differences in health years.

Methodology

DFLE is one of the most common measures of health expectancy since it distinguishes between life years that are free of any activity limitations and life years with some level of activity limitation; it is also an alternative to the life expectancy measure which addresses issues related solely to length of life. Further, DFLE provides a convenient way of combining mortality and morbidity into a single measure, and different methods are available for its calculations, the observed prevalence life table method (Sullivan's method), the double decrement life table method, the multistate life table method, the microsimulation method, which are based either on cross-sectional or longitudinal data.

DALY is a health gap measure that considers the difference between the actual population health status and a reference health status distribution, that combines premature mortality and disability and it is given by: DALY = YLL + YLD, where YLL (Years of Life Lost) measures the years of life lost due to a premature mortality and YLD (Years Lost due to Disability) measures the years of life lived with disability (C. Murray).

YLL e YLD are computed as follows:
YLL = N*L, with N=number of observed deceased, L=life expectancy for the observed mean age at death; YLD = I*DW*L, with I=number of incident cases, DW=disability weight, L=mean duration of disability. A 3% time discount rate to estimate the present value of years of life lost in the future, and age weighting to give more value to life lived at younger adult ages as compared to younger or older ages, can also be applied. An age-weighting (C=0.1658 and β=0.04) to allow years lived at different ages to take on different values were incorporated.

Harmonization process: Existing data are difficult to compare, due to lack of standardization in the concepts, design, and measurements of disability. The WHO has made an initiative to use a common international accepted definition of disability, but there is still enormous variation in the operationalization and assessment of disability. Across surveys, there are differences in the type, number, meaning, and response categories. These variations make it difficult to evaluate whether international differences in prevalence of disability are due to genuine cross-national differences caused by differences in sociodemographic or cultural factors, history, living environment, prevalence of chronic diseases, genetic factors, or by methodological problems. The European CLESA project produced, among others, harmonised ADL and IADL measures that allowed the cross-national comparisons and possible socio-cultural explanations for the dissimilarities.

Results

DFLE National estimates
The effect of education on DFLE among older Italians, using a hierarchical model as indicator of disability, with estimates based on the multistate life table method and IMaCh software was assessed. It was found a positive effect of higher education: older men and women with more than four years of education may live three more years without disability.

 

Harmonization process
Four items covering Katz's ADL index (bathing, dressing, transferring, toileting) were selected to construct a harmonised scale across six countries. The harmonised four-item scale appeared to be reliable and valid in each country: Cronbach's a of the four-item ADL measure varied from 0.81 in Spain to 0.92 in Finland.

DFLE Cross-national comparisons
DFLE was computed for five European Countries and Israel with the multistate life table methods using the IMaCh software. Figures show that:
In all six countries, DFLE (%) is lower among women than among men;
There is a north-south gradient in the % of DFLE among men;
There are slight cross-nation differences in the % of DFLE among women.

Activities in progress

  • Estimates of the DFLE and its Confidence Interval for Italy, Bulgaria, Argentina, Barbados, Brazil, Chile, Cuba, Mexico, and Uruguay for the 65+ population.
  • Estimates of the DALY on hospitalized Chronic Obstructive Pulmonary Disease (COPD) Italian patients by incorporating local estimates of the disease prevalence and of the relative risk of death, and applying population-specific disability weights. Disease Modelling (DisMod II) software was used to get estimates of incidence, mean disability duration and age at onset, whereas the level of disability was assessed through the administration of the Saint George Respiratory Questionnaire to a subset of our sample.

Conclusions

The positive effects of high education are well established in most research work and, being a modifiable factor, strategies focused on increasing level of education and, hence strengthening access to information and use of health services would produce significant benefits.

Two possible explanations could be advanced for the north-south differences: socio-economic and cultural differences. Differences in socio-economic status, as measured by educational level, were observed among the CLESA countries The percentage of subjects aged 75-84 years with incomplete primary school education ranges from 41% to 80% in the south and from 0% to 15% in the northern. Furthermore, there may be cultural differences in the meaning of dependence and the availability of family help, leading to an underreporting of dependency in northern countries and overreporting of dependency in the southern countries.

Publications

  • Minicuci N, Noale M, (2005) Influence of level of education on disability free life expectancy by sex: the ILSA study. Exp. Gerontol. 40:997-1003.
  • Pluijm SM, Bardage C, Nikula S, Blumstein T, Jylhä M, Minicuci N, Zunzunegui MV, Pedersen NL, Deeg DJ (2005) A harmonized measure of activities of daily living was a reliable and valid instrument for comparing disability in older people across countries. 58:1015-23.
  • Minicuci N, Noale M (2005) Disability free life expectancy in older Italians. Disabil Rehabil 27:221-7.
  • Nikula S, Jylhä M, Bardage C, Deeg DJ, Gindin J, Minicuci N, Pluijm SM, Rodríguez-Laso A, (2003) Are IADLs comparable across countries? Sociodemographic associates of harmonized IADL measures. 15:451-9.
  • Minicuci N, Noale M, Bardage C, Blumstein T, Deeg DJ, Gindin J, Jylhä M, Nikula S, Otero A, Pedersen NL, Pluijm SM, Zunzunegui MV, Maggi S, (2003) Cross-national determinants of quality of life from six longitudinal studies on aging: the CLESA project. 15:187-202.

Grants

Ministry of Health and Veneto Region: Health targeted projects
European Commission: V Framework Programme

Collaborations

  • D. Balzi, Florence Health Unit, Italy.
  • A. Franzo, Regional Health Unit, Friuli Venezia Giulia, Italy.
  • E. Maria León Díaz, National Statistics Office, Havana, Cuba.
  • M. Mutafova, Medical University, Sofia, Bulgaria.
  • A. Olivieri, Local Health Unit 15, Veneto Region, Italy.
  • the CLESA working group.

 

PI photo

Nadia Minicuci

Contact information

email  E-mail

email  049 8211226

Participating staff

Alessandra Andreotti

Marianna Noale