Prospective Outcomes of Informal and Formal Home Care: Mortality and Institutionalization. 3.4 Additional Considerations

12/19/1990

Both mortality and entering a nursing home are events that were distributed over the follow-up period. Thus, we might be concerned with estimating a time-to-event function rather than the relative odds of the occurrence of the events. A statistical technique which allows such an event history approach is the Cox proportional hazards regression. Unfortunately, the user data set produced by the National Center for Health Statistics did not include all of the dates necessary to record nursing home entry. However, the data set did include dates of death, allowing the application of this method to the mortality data.

TABLE 3-7. Comparison of Adjusted1 Odds Ratio and Hazard Ratio for Estimating the Impact of Caregiving Arrangements on Dying During Two-Year Follow-Up
Caregiving Arrangements Odds Ratio Hazard Ratio
Disability vs.
No Disability
1.02 1.07
Help vs.
No Help
2.48* 2.33*
Any Unpaid Help vs.
All Paid Help
1.09 1.08
Any Close Family Unpaid Help vs.
No Close Family Unpaid Help
0.93 0.91
All Unpaid Help vs.
Some Paid, Some Unpaid
0.73 0.76
All Unpaid Help, Close Family vs.
All Unpaid Help, Not Close Family
1.29 1.33
  1. Adjusted model includes variables from "second trimmed model": age, sex, social contacts, control over health, health status, ADLs, cancer, cerebrovascular accident, and hospital inpatient stays.

* = significant at <0.05

Table 3-7 shows the results of a comparison of adjusted odds ratios and hazard ratios for estimating the impact for caregiving arrangements on mortality during the two-year follow-up period. The results in the table indicate that the hazard ratio is nearly identical to the odds ratio. The estimate of the instantaneous hazard of dying is almost identical to the relative odds of dying over the entire period. After adjusting for social and health status variables, only receiving help is significantly associated with death. The odds ratio is 2.48 and the hazard ratio is 2.33. These results indicate that no information is being lost by ignoring the timing of death over the follow-up period. This may change even in these data as the follow-up period is extended. However, two years of follow-up is quite short for measuring an event like mortality. Thus, the potential differences in findings between the two techniques would not be likely to show up over such a short interval. Differences could be expected to widen over an extended follow-up period.

We were also interested in the potential for interaction effects between caregiving and living arrangements. Potentially, caregiving arrangements may have heterogeneous effects on the outcomes, depending upon the kind of household in which the respondent lives. We know that persons living alone are much more likely to use paid care than are those living with others. (For example, see Tennestadt et al., 1990). Therefore, we re-estimated the associations between caregiving arrangements and the outcomes for each of the three living arrangement categories: living alone, living with others, that is, other than spouse, and living with spouse. We were especially interested in finding whether some of the associations that we found not significant turn out to be significant only for one or the other of the living arrangements.

Table 3-8 shows the results for mortality. Among persons living alone, those receiving help are twice as likely to die in the follow-up period. In particular, those receiving all unpaid help are half as likely to die as those receiving a combination of paid and unpaid help, the odds ratio equaling 0.48. In contrast, among those receiving all unpaid help, those receiving it from close family members are 1.8 times as likely to die during the follow-up period as those receiving it from someone else. Overall, caregiving arrangements have very small effects on mortality among those living with others. Among those living with spouse, receiving help is strongly and significantly related to mortality, an odds ratio of 4.43. Odds ratios contrasting various combinations of help, however, are not particularly large and they are not statistically significant. While these findings may be suggestive, especially for persons living alone, and are difficult to interpret for those living with a spouse, they generally do not contradict the results from the overall analysis.

Table 3-9 shows the same results for entering a nursing home. Most of the effects are quite small, especially for those who live alone. Among those who live with others, there is an association between receiving unpaid help from close family members and mortality, with an odds ratio of 2.18; but it is not statistically significant. The same association is even larger among persons living with a spouse (odds ratio 2.38). The only significant association in the table is for those with disabilities who live with a spouse. They are 2.33 times more likely than those without a disability to enter a nursing home. Once again, there are some interesting contrasts between receiving unpaid help from close family members versus others, but the associations are not significant and the results remain quite similar to those derived from the overall analysis.

TABLE 3-8. Adjusted Odds of Dying After Two-Year Follow-Up by Characteristic of Caregiving and Living Arrangements
Caregiving Arrangements Mortality
Lives Alone OR Lives w/ Others OR Lives w/ Spouse OR
Disability vs.
No Disability
1.02 1.32 .85
Help vs.
No Help
2.10 1.14 4.43*
Any Unpaid Help vs.
All Paid Help
1.06 .84 1.26
Any Close Family Unpaid Help vs.
No Close Family Unpaid Help
1.21 .65 .84
All Unpaid Help vs.
Some Paid, Some Unpaid
.48 .93 .74
All Unpaid Help, Close Family vs.
All Unpaid Help, Not Close Family
1.77 .59 1.57
* = significant at <0.05


TABLE 3-9. Adjusted Odds of Entering a Nursing Home After Two-Year Follow-Up by Characteristics of Caregiving and Living Arrangements
Caregiving Arrangements Institutionalization
Lives Alone OR Lives w/ Others OR Lives w/ Spouse OR
Disability vs.
No Disability
1.39 1.24 2.33*
Help vs.
No Help
1.76 0.80 0.84
Any Unpaid Help vs.
All Paid Help
1.12 0.61 1.52
Any Close Family Unpaid Help vs.
No Close Family Unpaid Help
1.01 1.49 0.40
All Unpaid Help vs.
Some Paid, Some Unpaid
1.12 1.23 0.79
All Unpaid Help, Close Family vs.
All Unpaid Help, Not Close Family
1.00 2.18 2.38
* = significant at <0.05


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