As a start, the databases PsycInfo, Psyndex, DIMDI, Cochrane, MEDPILOT have been searched by using the keywords very old age, quality of life and longitudinal study to identify existing international and national research projects including the population of the very old
. In addition, we considered secondary internet-based literature and the Integrative Analysis of Longitudinal Studies on Aging Project (IALSA,
http://www.ialsa.org/ [9.12.2015]) platforms. The results show that a number of studies in German language were designed to look specifically at old age (see Table
1). The Berlin Aging Study (BASE I) [
15] investigated a locally representative sample from the general population at age 70+ years, with very old participants being overrepresented relative to their population counts [
1]. The BASE I included a wide range of objective and subjective measures of the quality of life, covering social, financial, psychological, medical and clinical indicators; however, the regional focus of BASE as well as the still moderate number of very old participants constrain generalizations to the broader German population of very old persons. The subsequent BASE II study started a new panel in 2011 with 1600 participants aged between 60 and 80 years [
6] and hence is not focusing on the very old. The
Generali Hochaltrigenstudie [
7] explores the perspective of 400 individuals aged 85 years and above using biographical interviews referring to life themes. Life themes correspond to the goals, orientations, needs and values of individuals. The respondents have been gathered through suggestions of welfare associations, churches, homes for the elderly, other institutions and recommendations, therefore the sample is highly selective. The two
Heidelberg Centenarian studies [
12,
25] have shown both the challenges and promises of population-based studies with the oldest-old. Naturally, the perspectives captured in these cross-sectional studies are those of late age survivors from a narrow range of respective birth cohorts, and as such may serve as a valuable reference for studying the quality of life in a broader segment in the old-old population. The
Austrian Interdisciplinary Study on the Oldest Old (ÖIHS) has recently been piloted in the regions of Styria and Vienna. In the survey, a total of 410 residents aged between 80 and 85 years, living both in private and nursing homes have been considered [
27]; therefore, it can serve as an example for the inclusion of very old people living in long-term care facilities even though the sample is relatively small and regionally focused. Also, very recently Conrad et al. [
3,
4] conducted a population based study to standardize the WHOQOL-OLD instrument. As the emphasis is on validating an old age module to the existing WHO-QOL instrument its main focus is on subjective quality of life. The European project
Enabling Autonomy, Participation, and Well-Being in Old Age (EnableAge) [
9] contains a regionally focused population based German subsample of individuals living alone. The
Longitudinal Analysis of Subjective Well-being in Very Old Age (LateLine) is a longitudinal follow-up of the German part of the EnableAge project. LateLine is focused on the influences of health constraints, the physical environment and anxiety concerning health and dying on subjective well-being and adaptation of the very old [
31].
Table 1
German-speaking studies targeting the quality of life in the very old population
Berlin Aging Study (BASE I) | 70+ | Broad range of objective and subjective indicators |
N = 516 (intensive protocol), random sample of West-Berlin residents, stratified by age and gender (1990/93) | |
Generali Hochaltrigenstudie (Interview study) | 85–99 | Themes of life (Daseinsthemen) |
N = 400 In-depth biographical interviews, ad hoc sample (2013) | |
Heidelberg Centenarian Study I | 100 | Four aspects of quality of life: cognitive status, functional capacity, mental health, subjective well-being |
N = 91, Local random sample (2000/01) | |
Heidelberg Centenarian Study II | 100 | Life satisfaction, meaning in life |
N = 112, Local random sample (n = 95) (2011/13) | |
Austrian Interdisciplinary Study on the Oldest Old (ÖIHS) | 80–85 | Objective indicators: e. g. health, care, standard of living (quantitative study part); subjective indicators: e. g. life satisfaction, opinions (qualitative study part) |
N = 410, Styria (150) and Vienna (260), local random sample; 40 qualitative interviews; (2013/14) | |
Quality of Life in the Elderly – Standardization of the WHOQOL-OLD | 60+ | Subjective quality of life (WHOQOL-BREF), six facets of the WHOQOL-OLD |
N = 1133, German random sample, additional sample 80+ (N = 309) (2012) | |
Enabling Autonomy, Participation, and Well-Being in Old Age: The Home Environment as a Determinant for Healthy Aging (EnableAge) | 80–89 | Home environment and housing, objective and subjective health, life satisfaction, affect |
N = 450, German local random sub-sample (2002) | |
Longitudinal Analysis of Subjective Well-being in Very Old Age (LateLine) | 87–97 | Hedonic well-being (e. g. life satisfaction, affect), eudaemonic well-being (e. g. autonomy, purpose in life), mental distress |
N = 124 (Baseline), German EnableAge follow up, seven measurement occasions from 2009/13 | |
Most studies employ a broad understanding of quality of life spanning resources as well as outcomes, such as satisfaction with life. As a basis for our concept of quality of life in very old age, attention should be paid to the different methodological approaches and their implications for representativeness and selectivity as well as the comprehensiveness of the concept of quality of life. Whereas the former studies focused on the population of the very old, the
German Aging Survey (DEAS) has been established as a national representative study in mid-life and old age. It is a valuable source for scientific investigation and policy making with respect to adults from age 40–85 years; however, since the DEAS is a population-based random sample, the absolute number of individuals aged 80 years and above in each of the 4 baseline samples to date (1996, 2002, 2008, 2014) do not enable a fine-grained analysis in this subpopulation [
16].
On the international level as well, only a few population-based studies explicitly focus on the very old, including the EnableAge project conducted in Sweden, UK, Latvia, and Hungary [
9], the
Georgia Centenarian study [
23], the
Fordham Centenarian study [
11], the
Swedish Panel Study of Living Conditions of the Oldest Old (SWEOLD) [
14], the
Newcastle 85+ study [
5], and the
Swiss Interdisciplinary Longitudinal Study on the Oldest Old (SWILSOO) [
8]; however, the majority of these studies are not based on random samples from the general population. Moreover, the possibility to transfer policy implications that have been derived from these studies across countries, or even across states within countries are limited due to apparent differences in political administration, social security systems, infrastructure, and culture. Although a number of population-based studies include respondents aged 80 years and over, not all studies explicitly target quality of life in very old age [
3]. Furthermore, a number of longitudinal studies have followed up their panel respondents up to their eighties and beyond. Among the 33 longitudinal studies on aging affiliated with the IALSA project, 14 studies did not originally include respondents aged 80 years and older at the first measurement occasion, and only a very limited number of studies exclusively targeted very old respondents from the beginning. Therefore, additional threats (e. g. panel mortality) to the generalizability of findings for these very old panel participants may need to be considered. Thus, all these different studies including the very old in Germany or abroad are either limited to certain regions, age segments or other types of selectivity, so that generalizable results for the very old in Germany cannot be derived; however, they all give important insights into different aspects of quality of life of the very old thus forming the knowledge base for the interdisciplinary project “Quality of life and subjective well-being of the very old in North Rhine-Westphalia” (NRW80+), which has recently started at the University of Cologne.