Is caring associated with an increased risk of mortality? Dr Gemma Catney Centre for Public Health, QUB NILS-RSU O’Reilly, D., Connolly, S. Rosato, M. and Patterson, C. (2008) Social Science and Medicine, 67:

Presentation outline Informal carers: who are they? Their health status? Data and methods Results Discussion Limitations of the approaches

Rationale An example of the kinds of research questions which can be addressed using mortality data Insight into how to deal with problems in the analysis of mortality data Further details on the NIMS and its research potential

Informal care Those who provide (without pay) care or assistance to people who are ill or need help with personal activities of daily living –Increasing proportions of: older people women in the workforce and changing family structure 2001 UK Census: c. 6 million Cross-sectional studies underestimate the total numbers - high turnover for those entering and leaving the caregiving role

Health status of informal caregivers Methodological difficulties in determining the health status of caregivers: cross-sectional studies only show associations Mental health: although variable, most studies show increased anxiety, depression, and other forms of psychological morbidity, depending on amount and length of time caring (and the illnesses of those being cared for): stress of caregiver burden Physical health: more difficult to assess. –Immunological system and physiological responses –The healthy caregiver effect

Data and methods NIMS: 2001 Census cohort attributes –Caregiver q: “Do you look after, or give any help or support to family members, friends, neighbours or others because of: long term physical or mental ill- health or disability; problems related to old age?” No; Yes, 1-19h a week; Yes, 20-49h; Yes, 50+ hours Socio-economic and demographic factors –Age, sex, marital status, socio-economic position (tenure, car ownership) Area characteristics –Pop. density, deprivation Health status: LLTI and GH Mortality: registered deaths matched to Census records (94% matched)

Data and methods (1)Descriptives of demographic and socio-economic characteristics of non- and caregivers (2) Multivariate logistic regression: variation in self-reported health by amount of care provided (3) Cox proportional hazards: mortality

‘healthy caregiver effect’ accounted for by: (1) controlling for differences in health status at baseline by including self- reported health in the analysis (2) stratifying by baseline health status and examining the mortality experience of carers in each health stratum separately (3) further analysing the dataset to test whether or not mortality differences between caregivers and non-caregivers remained constant over time

Results (i) who are caregivers in NI? (ii) variations in self-reported health (iii) variations in mortality

Who are caregivers in NI? 14.3% of NI pop enumerated in 2001 Census –59.4% 19 hours or less per week –15.1% 20-49h –25.5% 50+ h 68% of caregivers aged 35-64; 50+ hours tended to be older (20% aged 65+) Females disproportionately represented Married people more likely (two thirds) Socio-economic status differences: –19h or less per week = more affluent –50+ h = more disadvantaged –Higher levels of car access in those caring fewer hours: caring at a different address?

Variations in self-reported health (LLTI) Caregiver status FemaleMale Non-caregiver h0.70 (0.68, 0.71) 0.83 (0.80, 0.85) 20-49h0.77 (0.74, 0.80) 0.88 (0.83, 0.92) 50+h0.96 (0.93, 0.98) 1.14 (1.09, 1.18)

Variations in mortality Caregiver status FemaleMale Non-caregiver h0.74 (0.69, 0.80) 0.64 (0.58, 0.70) 20-49h0.83 (0.74, 0.94) 0.74 (0.64, 0.85) 50+h0.86 (0.81, 0.93) 0.75 (0.69, 0.81)

Discussion Caregivers drawn from all socio-economic groups. Those providing 19 or fewer hours tended to be more affluent and those providing more care less affluent. Caregivers report lower levels of LLTI (physical?) but higher levels of poor GH (broader? Physical and psychological health + health behaviours) than non- caregivers –Healthy worker (caregiver) effect? Caregiving associated with a reduced risk of mortality –Surprising? There are advantages to caregiving: Companionship, fulfilment, reward (Cohen et al., 2002) Satisfaction, closer to family, purpose (Lopez et al., 2005) Women more than men: women suffer more from caregiver strain as they tend to invest more in the process (Yee and Schulz, 2000), so perhaps women also reap the benefits in the relationship between caregiving and mortality

Limitations of the approach Self-reported nature of the data –But: SRH shown in other research to be strong predictors of future mortality Selection effects associated with socio- economic and health characteristics of the carers –Data are for 2001: selection effects prior to enumeration? –LLTI was less likely for caregivers – selection effect possible –However, the mortality advantage remained even after controlling for SRH

The help provided by the staff of the Northern Ireland Mortality Study (NIMS) and NILS Research Support Unit is acknowledged. NIMS is funded by the HSC R&D function of the Public Health Agency. The authors alone are responsible for the interpretation of the data. O’Reilly, D., Connolly, S. Rosato, M. and Patterson, C. (2008) Social Science and Medicine, 67: More information on NILS/NIMS data: