The structure and predictive value of intrinsic capacity in a longitudinal study of ageing
Objectives To assess the validity of the WHO concept of intrinsic capacity in a longitudinal study of ageing; to identify whether this overall measure disaggregated into biologically plausible and clinically useful subdomains; and to assess whether total capacity predicted subsequent care dependence...
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BMJ Publishing Group
2019-11-01
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| Series: | BMJ Open |
| Online Access: | https://bmjopen.bmj.com/content/9/11/e026119.full |
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| author | John R Beard A T Jotheeswaran Matteo Cesari Islene Araujo de Carvalho |
| author_facet | John R Beard A T Jotheeswaran Matteo Cesari Islene Araujo de Carvalho |
| author_sort | John R Beard |
| collection | DOAJ |
| description | Objectives To assess the validity of the WHO concept of intrinsic capacity in a longitudinal study of ageing; to identify whether this overall measure disaggregated into biologically plausible and clinically useful subdomains; and to assess whether total capacity predicted subsequent care dependence.Design Structural equation modelling of biomarkers and self-reported measures in the English Longitudinal Study of Ageing including exploratory factor analysis, exploratory bi-factor analysis and confirmatory factor analysis. Longitudinal mediation and moderation analysis of incident care dependence.Settings Community, United Kingdom.Participants 2560 eligible participants aged over 60 years.Main outcome measures Activities of daily living (ADL) and instrumental activities of daily living (IADL).Results One general factor (intrinsic capacity) and five subfactors emerged: locomotor, cognitive; psychological; sensory; and ‘vitality’. This structure is consistent with biological theory and the model had a good fit for the data (χ2=71.2 (df=39)). The summary score of intrinsic capacity and specific subfactors showed good construct validity. In a causal path model examining incident loss of ADL and IADL, intrinsic capacity had a direct relationship with the outcome—root mean square error of approximation (RMSEA)=0.02 (90% CI 0.001 to 0.05) and RMSEA=0.008 (90% CI0.001 to 0.03) respectively—and was a strong mediator for the effect of age, sex, wealth and education. Multimorbidity had an independent direct relationship with incident loss of ADLs but not IADLs, and also operated through intrinsic capacity. More of the indirect effect of personal characteristics on incident loss of ADLs and IADLs was mediated by intrinsic capacity than multimorbidity.Conclusions The WHO construct of intrinsic capacity appears to provide valuable predictive information on an individual’s subsequent functioning, even after accounting for the number of multimorbidities. The proposed general factor and subdomain structure may contribute to a transformative paradigm for future research and clinical practice. |
| format | Article |
| id | doaj-art-6ee24a848acf42f7ad04d5f3950efed1 |
| institution | Kabale University |
| issn | 2044-6055 |
| language | English |
| publishDate | 2019-11-01 |
| publisher | BMJ Publishing Group |
| record_format | Article |
| series | BMJ Open |
| spelling | doaj-art-6ee24a848acf42f7ad04d5f3950efed12024-11-27T23:30:14ZengBMJ Publishing GroupBMJ Open2044-60552019-11-0191110.1136/bmjopen-2018-026119The structure and predictive value of intrinsic capacity in a longitudinal study of ageingJohn R Beard0A T Jotheeswaran1Matteo Cesari2Islene Araujo de Carvalho31 Department of Ageing and Life Course, World Health Organization, Geneve, Switzerland1 Department of Ageing and Life Course, World Health Organization, Geneve, SwitzerlandAgeing and Health Unit, Department of Maternal, Newborn, Child and Adolescent Health and Ageing, World Health Organization, Geneva, Switzerland1 Department of Ageing and Life Course, World Health Organization, Geneve, SwitzerlandObjectives To assess the validity of the WHO concept of intrinsic capacity in a longitudinal study of ageing; to identify whether this overall measure disaggregated into biologically plausible and clinically useful subdomains; and to assess whether total capacity predicted subsequent care dependence.Design Structural equation modelling of biomarkers and self-reported measures in the English Longitudinal Study of Ageing including exploratory factor analysis, exploratory bi-factor analysis and confirmatory factor analysis. Longitudinal mediation and moderation analysis of incident care dependence.Settings Community, United Kingdom.Participants 2560 eligible participants aged over 60 years.Main outcome measures Activities of daily living (ADL) and instrumental activities of daily living (IADL).Results One general factor (intrinsic capacity) and five subfactors emerged: locomotor, cognitive; psychological; sensory; and ‘vitality’. This structure is consistent with biological theory and the model had a good fit for the data (χ2=71.2 (df=39)). The summary score of intrinsic capacity and specific subfactors showed good construct validity. In a causal path model examining incident loss of ADL and IADL, intrinsic capacity had a direct relationship with the outcome—root mean square error of approximation (RMSEA)=0.02 (90% CI 0.001 to 0.05) and RMSEA=0.008 (90% CI0.001 to 0.03) respectively—and was a strong mediator for the effect of age, sex, wealth and education. Multimorbidity had an independent direct relationship with incident loss of ADLs but not IADLs, and also operated through intrinsic capacity. More of the indirect effect of personal characteristics on incident loss of ADLs and IADLs was mediated by intrinsic capacity than multimorbidity.Conclusions The WHO construct of intrinsic capacity appears to provide valuable predictive information on an individual’s subsequent functioning, even after accounting for the number of multimorbidities. The proposed general factor and subdomain structure may contribute to a transformative paradigm for future research and clinical practice.https://bmjopen.bmj.com/content/9/11/e026119.full |
| spellingShingle | John R Beard A T Jotheeswaran Matteo Cesari Islene Araujo de Carvalho The structure and predictive value of intrinsic capacity in a longitudinal study of ageing BMJ Open |
| title | The structure and predictive value of intrinsic capacity in a longitudinal study of ageing |
| title_full | The structure and predictive value of intrinsic capacity in a longitudinal study of ageing |
| title_fullStr | The structure and predictive value of intrinsic capacity in a longitudinal study of ageing |
| title_full_unstemmed | The structure and predictive value of intrinsic capacity in a longitudinal study of ageing |
| title_short | The structure and predictive value of intrinsic capacity in a longitudinal study of ageing |
| title_sort | structure and predictive value of intrinsic capacity in a longitudinal study of ageing |
| url | https://bmjopen.bmj.com/content/9/11/e026119.full |
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