5.3 The chronic conditions
The chronic conditions were included as a series of binary indicators in core models one and two. Owing to the lack of independence between chronic conditions, these models were run separately for each chronic condition.
5.3.1 Results from the chronic conditions
All chronic conditions had negative coefficients with only asthma and high blood pressure not significant at the 10% level.
Figure 5 shows the magnitude of the marginal effects for each chronic condition and For all conditions except asthma the marginal effect in core model two is less than the marginal effect in core model one. Some of this difference will be owing to the inclusion of additional control variables in core model two that are not in core model one. For example, smoking or receiving a non-health tested benefit may be associated with certain chronic conditions.
When interpreting these results it is important to note that they are derived by considering each chronic condition in turn, rather than simultaneously. The results can be directly compared to not having the chronic condition; comparison to other conditions can only be done indirectly. There were too few respondents with multiple chronic conditions to consider having a combination of conditions. The proportion of the longitudinal population with each chronic condition can be found in Appendix A, Appendix Table 3.
Figure 6 gives the prevalence weighted magnitude of the statistically significant chronic conditions.
- Figure 5 – The estimated negative marginal effects of chronic conditions on wealth
- Source: SoFIE Waves 1–3, OSMs, longitudinal weights, supplied by Statistics New Zealand
For all conditions except asthma the marginal effect in core model two is less than the marginal effect in core model one. Some of this difference will be owing to the inclusion of additional control variables in core model two that are not in core model one. For example, smoking or receiving a non-health tested benefit may be associated with certain chronic conditions.
When interpreting these results it is important to note that they are derived by considering each chronic condition in turn, rather than simultaneously. The results can be directly compared to not having the chronic condition; comparison to other conditions can only be done indirectly. There were too few respondents with multiple chronic conditions to consider having a combination of conditions. The proportion of the longitudinal population with each chronic condition can be found in Appendix A, Appendix Table 3.
- Figure 6 – The estimated negative marginal effects of chronic conditions on wealth – weighted by prevalence
- Source: SoFIE Waves 1–3, OSMs, longitudinal weights, supplied by Statistics New Zealand
Results from the decomposition of the chronic conditions
All chronic conditions, other than depression and schizophrenia, were decomposed by whether diagnosis occurred within the last five years or more than five years ago. This was done to try to identify the immediate and long-term wealth effects associated with these chronic conditions. The presence of depression or schizophrenia could not be decomposed.
- Figure 7 – The estimated negative marginal effects of chronic conditions on wealth – by timing of diagnosis – core model one
- Source: SoFIE Waves 1–3, OSMs, longitudinal weights, supplied by Statistics New Zealand
It was unclear what effect this decomposition would have. Those who were diagnosed more than five years ago might no longer suffer the effects of their condition or might have experienced a greater effect on their wealth from having the condition for a longer period of time. Those with recent diagnoses were more likely to currently suffer from the effects of their condition, but any effect on their wealth might not yet be noticeable. Figure 7 illustrates the marginal effects on net wealth of each chronic condition depending on the timing of diagnosis.
Other than for asthma, the difference between the coefficients was not significant at the 10% level. Given the size of the differences between the marginal effects shown in Figure 7 we might have expected the differences for stroke and migraines to be significant. While the results are not generally statistically significant their relative magnitudes are consistent with the pattern that would be expected. Specifically, stroke produces permanent neurological deficit and would be expected to show a stronger effect on wealth when diagnosed more than five years previously. In contrast, asthma and migraine typically produce only short-lasting “health failures” and show a stronger effect when diagnosed within the last five years[17].
Having been diagnosed with asthma does not appear to have a long term association with a person’s wealth. This may be owing to respondents being diagnosed with asthma in their youth and growing out of it as they age.
The marginal effects for heart disease and diabetes are significant and similar regardless of the length of time since diagnosis.[18] This might suggest that these conditions have both an immediate and sustained impact on wealth.
