The importance of patient income in specialist mental health care

Ggz provides both basic and specialist care through clinical psychologists, psychiatrists or multidisciplinary care teams; and the general practitioner acts as gatekeeper. GGZ is covered by basic insurance, and thus patients are protected from high co-payments. 

Earlier research

Earlier research from 1996 indicated that higher mental healthcare use among low (versus high) income patients can largely be traced back to higher mental healthcare needs. In addition, low-income patients more often use care outside the mental health system (a.k.a. social workers), while high-income patients more often move on to specialist mental health services.[1]

While there is some evidence about the accessibility of mental health care, there is no evidence about the extent to which mental healthcare outcomes and treatment time differ between income groups after patients enter the specialist mental healthcare. We examined this for the Netherlands in an article recently published in The Lancet Psychiatry.

Our study

In our study, we used administrative register data from the Central Bureau of Statistics (CBS). We had access to data on specialist mental health care use, disease severity and income information of all Dutch residents who started at least one treatment in the specialist mental health care between 2011 and 2016. Disease severity is assessed by healthcare professionals using the Global Assessment of Functioning (GAF) score, and incomes of all patients are divided into five equal income groups based on the national income distribution.

We used these data to examine four hypotheses: (i) do lower-income patients access specialist mental health services with a higher disease severity compared to higher-income patients?; (ii) does total treatment time differ between income groups?; (iii) does disease severity improve between the start and end of treatment (Diagnosis Treatment Combination, DBC), and is the health benefit greater for higher-income patients?; and (iv) do lower-income patients have a higher probability of starting a new treatment episode (DBC) within 90 days of the conclusion of the first treatment episode? We always compared patients with different incomes within the same diagnosis categories for steps (i)-(iv) and with the same GAF score for steps (ii)-(iv).

Lowest income quintiles more severely ill

The administrative records show that of all patients who initiated a new treatment episode between 2011 and 2016, 31 percent were in the poorest quintile (20 percent) and 14 percent were in the richest quintile of the national income distribution. This does not necessarily mean that specialty mental health services were more accessible to people with lower incomes because the need for mental health care is also concentrated among the poorest segments of the population. However, we could not quantify this further because diagnosis and disease severity are not reported for all Dutch residents, but only for the group initiating a treatment episode.

We can say with certainty that the lowest income quintiles were more severely ill at their first diagnosis based on their GAF score. We also find that the lowest income quintile received 12 percent additional treatment time compared to the richest quintile, but that this difference reversed after controlling for diagnosis and illness severity: the lowest quintile then received 2 percent less care. This means that for similar mental health problems, the lowest-income quintiles received less treatment time than the four other income groups. 

Health gains between the start and end of a treatment episode were substantially higher for higher incomes, and this result held true after adjusting for differences in diagnosis, disease severity, and treatment time: 43 percent of the richest quintile saw their health improve while only 26 percent of the lowest incomes did. 

Furthermore, after completing the first treatment episode, there was a higher probability for the lowest versus highest income quintile to initiate a new treatment episode within 90 days (36 percent in the lowest income quintile versus 33 percent in the highest income quintile). Finally, we found that these general trends are also broadly found for the individual diagnostic categories of depression, anxiety, and other disorders.

Not achieve the same health gains

Our study is a descriptive analysis and therefore cannot comment on possible differences in treatment effectiveness of specialty mental health services between higher and lower income groups. What does become clear is that patients with different incomes do not enter with equal disease severity, receive different treatment durations, and also do not achieve the same health gains during the first treatment episode; all to the disadvantage of lower income groups. Our study does not identify the causes behind these trends, but nevertheless raises several interesting questions and hypotheses. 

First, absence of diagnosis-specific patterns suggests that underlying causes and explanations are not diagnosis-specific. Second, the size of the deductible is probably unimportant because co-payments matter mostly for access to care and less after a treatment episode is started. Third, early detection of mental health problems may reduce the difference in disease severity at the start of the first treatment episode. 

Fourth, there may be several possible explanations for the difference in total treatment time, each of which requires a different policy approach. It is possible that lower income classes need more treatment time to achieve the same health gains as higher income classes, but it is also possible that treatment adherence differs between income groups. There may also be differences in the quality and appropriateness of care received. We hope that future research will provide answers to these important questions.