The descriptive statistics of the total responses (i.e. 121,410 observation-years) along with the minimum and maximum average values across 11 waves are presented in Table 2. The average age across all respondents’ observation-years was 44 years. Carers’ age ranged from 15 to 92 years with an average age of 52 years across all waves. The number of carers varied from 566 (wave 7) to 989 (wave 12) (see Table 1), and they constituted nearly 7 per cent of the total observation-years. Those who served as carers, on an average spent 2.7 years on active caregiving responsibilities over the eleven-year window. While in active caregiving status, people spent on average 14.5 (SD=26.8) hours a week in caregiving activities, compared to non-carers who spent less than an hour (0.38 of an hour with a SD=3.6). In total, 42.5 per cent of the respondents were in full-time employment. The alcohol and smoking status revealed 18 per cent of the respondents across all waves were non-drinkers and 81 percent were non-smokers.
Carer and Non-carer Health
Figures 1 and 2 present mean values of carer and non-carer’s health status across the waves by gender. Overall, non-carers showed better outcomes than carers in all three health measures. Also, non-carers showed consistently even and slightly declining trends over time with males doing better than females in mental health and physical functioning. Whereas carers showed fluctuating and slightly decreasing trends over the years in all three health measures with the exception of mental health for males, where we see a slightly increasing trend over the years.
Results of the fully adjusted FE models are presented in Table 3 for both SF36 mental (first three columns) and general health (subsequent three columns). In Table 3, the first row presents the impact of Carer Status on mental health and general health outcomes. The following section titled Effects in Non-Carer Status (main terms), presents the estimates of effects of non-carer’s characteristics such as their age and caregiving time and their health behaviours (physical activity level, smoking and drinking level), employment status and level of social engagement. The section titled Differences in Carer versus Non-carer Status (interaction terms), presents the non-carer and carer status differential estimated effects. Overall the caregiving status was interacted with other individual characteristics (such as their age and caregiving time, health behaviours, employment status and level of social engagement) to produce Carer differential effects. There were statistically significant carer/non-carer status differences in mental health (estimate (Beta) = -0.587, 95% confidence interval (CI): (-0.972, -0.203), p=0.003) and general health (Beta = -0.670, 95%CI: (-1.058, -0.283), p=0.001). On the other hand, there was no significant carer-noncarer status difference in SF-36 physical functioning scores (as shown in Table 4). Consequently, we did not proceed with further analyses for this component. Individuals showed significant disadvantages in both mental and general health outcomes due to being active carers across waves. These carer status disadvantages remained highly statistically significant even after controlling for a range of other household and personal level social, economic, demographic characteristics, smoking, drinking and health behaviour in the model (Table 3). On average, carers reported worse mental and general health scores that are 3 points less than those of non-carers. Additionally, we found that the time spent per week in caregiving duties was negatively related to the mental health score but not to the general health score. The negative influence of time spent on caregiving duties was persistent across carer status levels even though on average people in non-carer’s status spent much less time on caregiving than those in carer’s status (0.38 of an hour compared to 14.5 hours a week). Other confounders in the model, namely, household gross income, any serious personal injury/illness in the past year and time spent per week volunteering/charity work had impact on both mental and general health measures in the expected direction in the overall model. The first two of these expected effects were statistically significant, whereas time spent in volunteering/charity work was not significant.
Aging and Carer Health
The carer health trends over time revealed interesting patterns in this study. There was a clear pattern of decreasing mental and general health status for both carers and non-carers with their age. Figures 3 and 4 present mental and general health marginal mean trends respectively (adjusted predictions) over time (with age as time) for carer and non-carer groups. Both mental and general health scores decreased significantly with age, but at different rates for carers and non-carers. In unadjusted models for mental health, estimates of rates of change were: Beta = -0.054 (95% CI: (-0.084, -0.024), p<0.001) for non-carers; Beta = -0.034 (95% CI: (-0.071, 0.004), p=0.077) for carers, and the difference in rates of change was not statistically significant (p=0.088). For general health, estimates were: Beta = -0.477 (95% CI: (-0.509, -0.443), p<0.001); Beta = -0.437 (95% CI: (-0.477, -0.397), p<0.001), for non-carers and carers respectively, and the difference in slopes was significant (p=0.002). As shown in Figures 3 and 4, carer status modified the effect of aging on mental and general health with a slower rate of decline for carers compared to non-carers (moderation effect). The decreasing pattern in mental and general health with aging remained for non-carer status, in fully adjusted models as shown in Table 3. However, the adjusted decrease was non-significant for mental health, but significant for general health. The difference in rates of change due to carer status was on the margin of statistical significance for mental health at the 10 percent level, but remained significant for general health at 5 percent level.
Health Behaviour and Carer Health
Interactions of individuals’ health behaviours, such as their drinking and smoking status and physical activity level, with their carer/non-carer status, revealed quite intriguing relations with both mental and general health scores.
Results for alcohol drinking status when interacted with the number of standard drinks consumed per day revealed that in non-carers, any level of drinking, compared to those who did not drink, had a negative effect on mental health score with increasing patterns. However, the drinking status exhibited quite an intriguing pattern in terms of its effect on non-carers’ general health score (Table 3, 4th column). For example, if a person was a social drinker and drank only 2-3 days per month with only 1 to 2 standard drinks or even 1-2 days per week with 1 to 2 standard drinks then that had a positive effect on general health score compared to those who did not drink. On the other hand, if a person drank 5 or more standard drinks for only 2 to 3 days per month or drank on a weekly basis then that had a negative effect on general health score. In the case of carer status, the effect modification was significant for mental health only in light drinkers (“drink only rarely”, or “drink 2-3 days per month”) who consumed 3 to 4 standard drinks with on average a 2-points higher score. The same effect modification was apparent for general health in the same groups as for mental health. However, the 2-points difference on average (in favour of carers) was only marginally significant at the 10 percent level.
As expected for smoking status, results revealed that, in non-carers, smoking daily had a significant negative effect on mental health score, whereas any level of smoking had a negative effect on general health score, increasing with the level of smoking status. For those in carer status, light (smoke less often than weekly) and medium (smoke at least weekly, but not daily) smoking was more detrimental to mental health than was smoking daily. This was not the case for general health, where the negative effect of smoking got stronger as the levels of smoking increased. Overall, we have also controlled for the number of cigarettes a person usually smokes per week and found a statistically significant negative effect on the persons’ general health (irrespective of carer/non-carer status).
As for physical activity status, when someone was a non-carer, any level of exercising, compared to those who did not undertake any activity, had a positive and increasing influence on both mental and general health scores, with more activities generating better health outcomes. Carer/non-carer status differences in effects appeared to be all positive for mental health, meaning that physical activities were even more beneficial when someone served as a carer, though the benefit was significant only at the physical activity level of 3 times per week.
Social Engagement, Employment and Carer Health
Overall, the level of social engagement and employment status when serving as a carer did not show any significant carer and non-carer status differential effect on health. However, results on employment status revealed that a non-carer and full-time employed person reported both better mental and general health scores compared to part-time employees, pensioners, students and housewives. But, employment status had no significant modifying effect on mental and general health scores when someone served as a carer.
Similarly, for social interactions and communication with friends and relatives, when non-carer, the more often a person got together with friends/relatives, compared to infrequent interactions (less often than once in three months), the better mental and general health status they enjoyed. However, results showed no significant carer/non-carer status differences.