The explanation of a paradox? A commentary on Mackenbach with perspectives from research on financial credits and risk factor trends

Can countries shape the association between cumulative adversity and old-age health?

Introduction

The present study examined the relationships of Lifetime Cumulative Adversity (LCA) and country inequalities, as well as the interactions between them, with the self-rated health (SRH) in old age.

Methods

Using data from the Survey of Health, Aging and Retirement in Europe (SHARE), the study regressed self-rated health on Lifetime Cumulative Adversity and country-level inequality indices across European countries in two points in time. The analysis also considered adversity-inequality interactions, controlling for confounders. The sample was comprised of 28,789 adults, aged 50 to 80, from 25 European countries and Israel.

Results

The findings pointed out that LCA is negatively associated with SRH, but democracy and welfare regimes modify the ill effects of LCA on health. These effects are reduced as the LCA level increases. The effects remained significant over two measurement time-points over three years, showing that life-course trajectories may be shaped by individual accumulated risk exposure to stress, along with inequalities at the society level.

Discussion

The study provides constructive and important guidance for decreasing the harmful effect of lifetime adversity in old age, by the modification of the country's welfare policies.

Impacts of unconditional cash transfers on health care utilisation in informal sector households in Togo

BACKGROUND

Most Togolese population earns their income from informal sector, and they are very often exposed to health outcomes. Cash transfers impact healthcare utilization by improving household's social capital, socio-economic status, lifestyle choice, and physical health. The aim of this paper was to analyse the impact of unconditional cash transfers on health care utilisation in informal sector households.

METHODS

We used the propensity-score method to compare health care utilisation by households that received cash transfers from nonbeneficiary households and simulated a potential confounder to assess the robustness of the impacts of the estimated treatment (i.e., cash transfer). Data were obtained from a national survey that covered 1405 households.

RESULTS

The results show that women benefited the most from cash transfers (73.1%). Our estimates indicate that health care utilisation increased by 28.3% among workers in the informal sectors who benefited from unconditional cash transfers compared to nonbeneficiaries. The greatest impact was found on agriculture households with an increase by 31.3% in the health care utilisation. In general, cash transfer beneficiaries are more likely to use public health centres; there was an increase in public health facility attendance of 21.3%.

CONCLUSIONS

Cash transfers are a valuable social protection instrument that improve health care utilisation of populations in the informal sector. Policymakers could use cash transfer as the infusion of income and/or assets that may impact health outcomes. Cash transfers are an opportunity to alleviate barriers of access to health care by older people. Future research must examine impact of cash transfer on health of vulnerable groups such as older people, children, and people with disabilities.

Unconditional cash transfers for reducing poverty and vulnerabilities: effect on use of health services and health outcomes in low- and middle-income countries

BACKGROUND

Unconditional cash transfers (UCTs; provided without obligation) for reducing poverty and vulnerabilities (e.g. orphanhood, old age, or HIV infection) are a social protection intervention addressing a key social determinant of health (income) in low- and middle-income countries (LMICs). The relative effectiveness of UCTs compared with conditional cash transfers (CCTs; provided only if recipients follow prescribed behaviours, e.g. use a health service or attend school) is unknown.

OBJECTIVES

To assess the effects of UCTs on health services use and health outcomes in children and adults in LMICs. Secondary objectives are to assess the effects of UCTs on social determinants of health and healthcare expenditure, and to compare the effects of UCTs versus CCTs.

SEARCH METHODS

For this update, we searched 15 electronic academic databases, including CENTRAL, MEDLINE and EconLit, in September 2021. We also searched four electronic grey literature databases, websites of key organisations and reference lists of previous systematic reviews, key journals and included study records.

SELECTION CRITERIA

We included both parallel-group and cluster-randomised controlled trials (C-RCTs), quasi-RCTs, cohort studies, controlled before-and-after studies (CBAs), and interrupted time series studies of UCT interventions in children (0 to 17 years) and adults (≥ 18 years) in LMICs. Comparison groups received either no UCT, a smaller UCT or a CCT. Our primary outcomes were any health services use or health outcome.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened potentially relevant records for inclusion, extracted data and assessed the risk of bias. We obtained missing data from study authors if feasible. For C-RCTs, we generally calculated risk ratios for dichotomous outcomes from crude frequency measures in approximately correct analyses. Meta-analyses applied the inverse variance or Mantel-Haenszel method using a random-effects model. Where meta-analysis was impossible, we synthesised results using vote counting based on effect direction. We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

We included 34 studies (25 studies of 20 C-RCTs, six CBAs, and three cohort studies) involving 1,140,385 participants (45,538 children, 1,094,847 adults) and 50,095 households in Africa, the Americas and South-East Asia in our meta-analyses and narrative syntheses. These analysed 29 independent data sets. The 24 UCTs identified, including one basic universal income intervention, were pilot or established government programmes or research experiments. The cash value was equivalent to 1.3% to 81.9% of the annualised gross domestic product per capita. All studies compared a UCT with no UCT; three studies also compared a UCT with a CCT. Most studies carried an overall high risk of bias (i.e. often selection or performance bias, or both). Most studies were funded by national governments or international organisations, or both. Throughout the review, we use the words 'probably' to indicate moderate-certainty evidence, 'may/maybe' for low-certainty evidence, and 'uncertain' for very low-certainty evidence. Health services use We assumed greater use of any health services to be beneficial. UCTs may not have impacted the likelihood of having used any health service in the previous 1 to 12 months, when participants were followed up between 12 and 24 months into the intervention (risk ratio (RR) 1.04, 95% confidence interval (CI) 1.00 to 1.09; I² = 2%; 5 C-RCTs, 4972 participants; low-certainty evidence). Health outcomes At one to two years, UCTs probably led to a clinically meaningful, very large reduction in the likelihood of having had any illness in the previous two weeks to three months (RR 0.79, 95% CI 0.67 to 0.92; I² = 53%; 6 C-RCTs, 9367 participants; moderate-certainty evidence). UCTs may have increased the likelihood of having been food secure over the previous month, at 13 to 36 months into the intervention (RR 1.25, 95% CI 1.09 to 1.45; I² = 85%; 5 C-RCTs, 2687 participants; low-certainty evidence). UCTs may have increased participants' level of dietary diversity over the previous week, when assessed with the Household Dietary Diversity Score and followed up 24 months into the intervention (mean difference (MD) 0.59 food categories, 95% CI 0.18 to 1.01; I² = 79%; 4 C-RCTs, 9347 participants; low-certainty evidence). Despite several studies providing relevant evidence, the effects of UCTs on the likelihood of being moderately stunted and on the level of depression remain uncertain. We found no study on the effect of UCTs on mortality risk. Social determinants of health UCTs probably led to a clinically meaningful, moderate increase in the likelihood of currently attending school, when assessed at 12 to 24 months into the intervention (RR 1.06, 95% CI 1.04 to 1.09; I² = 0%; 8 C-RCTs, 7136 participants; moderate-certainty evidence). UCTs may have reduced the likelihood of households being extremely poor, at 12 to 36 months into the intervention (RR 0.92, 95% CI 0.87 to 0.97; I² = 63%; 6 C-RCTs, 3805 participants; low-certainty evidence). The evidence was uncertain for whether UCTs impacted livestock ownership, participation in labour, and parenting quality. Healthcare expenditure Evidence from eight cluster-RCTs on healthcare expenditure was too inconsistent to be combined in a meta-analysis, but it suggested that UCTs may have increased the amount of money spent on health care at 7 to 36 months into the intervention (low-certainty evidence). Equity, harms and comparison with CCTs The effects of UCTs on health equity (or unfair and remedial health inequalities) were very uncertain. We did not identify any harms from UCTs. Three cluster-RCTs compared UCTs versus CCTs with regard to the likelihood of having used any health services or had any illness, or the level of dietary diversity, but evidence was limited to one study per outcome and was very uncertain for all three.

AUTHORS' CONCLUSIONS

This body of evidence suggests that unconditional cash transfers (UCTs) may not impact a summary measure of health service use in children and adults in LMICs. However, UCTs probably or may improve some health outcomes (i.e. the likelihood of having had any illness, the likelihood of having been food secure, and the level of dietary diversity), two social determinants of health (i.e. the likelihoods of attending school and being extremely poor), and healthcare expenditure. The evidence on the relative effectiveness of UCTs and CCTs remains very uncertain.

Unconditional cash transfers for reducing poverty and vulnerabilities: effect on use of health services and health outcomes in low- and middle-income countries

BACKGROUND

Unconditional cash transfers (UCTs; provided without obligation) for reducing poverty and vulnerabilities (e.g. orphanhood, old age or HIV infection) are a type of social protection intervention that addresses a key social determinant of health (income) in low- and middle-income countries (LMICs). The relative effectiveness of UCTs compared with conditional cash transfers (CCTs; provided so long as the recipient engages in prescribed behaviours such as using a health service or attending school) is unknown.

OBJECTIVES

To assess the effects of UCTs for improving health services use and health outcomes in vulnerable children and adults in LMICs. Secondary objectives are to assess the effects of UCTs on social determinants of health and healthcare expenditure and to compare to effects of UCTs versus CCTs.

SEARCH METHODS

We searched 17 electronic academic databases, including the Cochrane Public Health Group Specialised Register, the Cochrane Database of Systematic Reviews (the Cochrane Library 2017, Issue 5), MEDLINE and Embase, in May 2017. We also searched six electronic grey literature databases and websites of key organisations, handsearched key journals and included records, and sought expert advice.

SELECTION CRITERIA

We included both parallel group and cluster-randomised controlled trials (RCTs), quasi-RCTs, cohort and controlled before-and-after (CBAs) studies, and interrupted time series studies of UCT interventions in children (0 to 17 years) and adults (18 years or older) in LMICs. Comparison groups received either no UCT or a smaller UCT. Our primary outcomes were any health services use or health outcome.

DATA COLLECTION AND ANALYSIS

Two reviewers independently screened potentially relevant records for inclusion criteria, extracted data and assessed the risk of bias. We tried to obtain missing data from study authors if feasible. For cluster-RCTs, we generally calculated risk ratios for dichotomous outcomes from crude frequency measures in approximately correct analyses. Meta-analyses applied the inverse variance or Mantel-Haenszel method with random effects. We assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

We included 21 studies (16 cluster-RCTs, 4 CBAs and 1 cohort study) involving 1,092,877 participants (36,068 children and 1,056,809 adults) and 31,865 households in Africa, the Americas and South-East Asia in our meta-analyses and narrative synthesis. The 17 types of UCTs we identified, including one basic universal income intervention, were pilot or established government programmes or research experiments. The cash value was equivalent to 1.3% to 53.9% of the annualised gross domestic product per capita. All studies compared a UCT with no UCT, and three studies also compared a UCT with a CCT. Most studies carried an overall high risk of bias (i.e. often selection and/or performance bias). Most studies were funded by national governments and/or international organisations.Throughout the review, we use the words 'probably' to indicate moderate-quality evidence, 'may/maybe' for low-quality evidence, and 'uncertain' for very low-quality evidence. UCTs may not have impacted the likelihood of having used any health service in the previous 1 to 12 months, when participants were followed up between 12 and 24 months into the intervention (risk ratio (RR) 1.04, 95% confidence interval (CI) 1.00 to 1.09, P = 0.07, 5 cluster-RCTs, N = 4972, I² = 2%, low-quality evidence). At one to two years, UCTs probably led to a clinically meaningful, very large reduction in the likelihood of having had any illness in the previous two weeks to three months (odds ratio (OR) 0.73, 95% CI 0.57 to 0.93, 5 cluster-RCTs, N = 8446, I² = 57%, moderate-quality evidence). Evidence from five cluster-RCTs on food security was too inconsistent to be combined in a meta-analysis, but it suggested that at 13 to 24 months' follow-up, UCTs could increase the likelihood of having been food secure over the previous month (low-quality evidence). UCTs may have increased participants' level of dietary diversity over the previous week, when assessed with the Household Dietary Diversity Score and followed up 24 months into the intervention (mean difference (MD) 0.59 food categories, 95% CI 0.18 to 1.01, 4 cluster-RCTs, N = 9347, I² = 79%, low-quality evidence). Despite several studies providing relevant evidence, the effects of UCTs on the likelihood of being moderately stunted and on the level of depression remain uncertain. No evidence was available on the effect of a UCT on the likelihood of having died. UCTs probably led to a clinically meaningful, moderate increase in the likelihood of currently attending school, when assessed at 12 to 24 months into the intervention (RR 1.06, 95% CI 1.03 to 1.09, 6 cluster-RCTs, N = 4800, I² = 0%, moderate-quality evidence). The evidence was uncertain for whether UCTs impacted livestock ownership, extreme poverty, participation in child labour, adult employment or parenting quality. Evidence from six cluster-RCTs on healthcare expenditure was too inconsistent to be combined in a meta-analysis, but it suggested that UCTs may have increased the amount of money spent on health care at 7 to 24 months into the intervention (low-quality evidence). The effects of UCTs on health equity (or unfair and remedial health inequalities) were very uncertain. We did not identify any harms from UCTs. Three cluster-RCTs compared UCTs versus CCTs with regard to the likelihood of having used any health services, the likelihood of having had any illness or the level of dietary diversity, but evidence was limited to one study per outcome and was very uncertain for all three.

AUTHORS' CONCLUSIONS

This body of evidence suggests that unconditional cash transfers (UCTs) may not impact a summary measure of health service use in children and adults in LMICs. However, UCTs probably or may improve some health outcomes (i.e. the likelihood of having had any illness, the likelihood of having been food secure, and the level of dietary diversity), one social determinant of health (i.e. the likelihood of attending school), and healthcare expenditure. The evidence on the relative effectiveness of UCTs and CCTs remains very uncertain.

Invited Commentary: Using Financial Credits as Instrumental Variables for Estimating the Causal Relationship Between Income and Health

Social epidemiologists are interested in determining the causal relationship between income and health. Natural experiments in which individuals or groups receive income randomly or quasi-randomly from financial credits (e.g., tax credits or cash transfers) are increasingly being analyzed using instrumental variable analysis. For example, in this issue of the Journal, Hamad and Rehkopf (Am J Epidemiol. 2016;183(9):775-784) used an in-work tax credit called the Earned Income Tax Credit as an instrument to estimate the association between income and child development. However, under certain conditions, the use of financial credits as instruments could violate 2 key instrumental variable analytic assumptions. First, some financial credits may directly influence health, for example, through increasing a psychological sense of welfare security. Second, financial credits and health may have several unmeasured common causes, such as politics, other social policies, and the motivation to maximize the credit. If epidemiologists pursue such instrumental variable analyses, using the amount of an unconditional, universal credit that an individual or group has received as the instrument may produce the most conceptually convincing and generalizable evidence. However, other natural income experiments (e.g., lottery winnings) and other methods that allow better adjustment for confounding might be more promising approaches for estimating the causal relationship between income and health.

Using Marginal Structural Modeling to Estimate the Cumulative Impact of an Unconditional Tax Credit on Self-Rated Health

In previous studies, researchers estimated short-term relationships between financial credits and health outcomes using conventional regression analyses, but they did not account for time-varying confounders affected by prior treatment (CAPTs) or the credits' cumulative impacts over time. In this study, we examined the association between total number of years of receiving New Zealand's Family Tax Credit (FTC) and self-rated health (SRH) in 6,900 working-age parents using 7 waves of New Zealand longitudinal data (2002-2009). We conducted conventional linear regression analyses, both unadjusted and adjusted for time-invariant and time-varying confounders measured at baseline, and fitted marginal structural models (MSMs) that more fully adjusted for confounders, including CAPTs. Of all participants, 5.1%-6.8% received the FTC for 1-3 years and 1.8%-3.6% for 4-7 years. In unadjusted and adjusted conventional regression analyses, each additional year of receiving the FTC was associated with 0.033 (95% confidence interval (CI): -0.047, -0.019) and 0.026 (95% CI: -0.041, -0.010) units worse SRH (on a 5-unit scale). In the MSMs, the average causal treatment effect also reflected a small decrease in SRH (unstabilized weights: β = -0.039 unit, 95% CI: -0.058, -0.020; stabilized weights: β = -0.031 unit, 95% CI: -0.050, -0.007). Cumulatively receiving the FTC marginally reduced SRH. Conventional regression analyses and MSMs produced similar estimates, suggesting little bias from CAPTs.

Unconditional cash transfers for assistance in humanitarian disasters: effect on use of health services and health outcomes in low- and middle-income countries

BACKGROUND

Unconditional cash transfers (UCTs) are a common social protection intervention that increases income, a key social determinant of health, in disaster contexts in low- and middle-income countries (LMICs).

OBJECTIVES

To assess the effects of UCTs in improving health services use, health outcomes, social determinants of health, health care expenditure, and local markets and infrastructure in LMICs. We also compared the relative effectiveness of UCTs delivered in-hand with in-kind transfers, conditional cash transfers, and UCTs paid through other mechanisms.

SEARCH METHODS

We searched 17 academic databases, including the Cochrane Public Health Group Specialised Register, the Cochrane Database of Systematic Reviews (The Cochrane Library 2014, Issue 7), MEDLINE, and EMBASE between May and July 2014 for any records published up until 4 May 2014. We also searched grey literature databases, organisational websites, reference lists of included records, and academic journals, as well as seeking expert advice.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials (RCTs), as well as cohort, interrupted time series, and controlled before-and-after studies (CBAs) on UCTs in LMICs. Primary outcomes were the use of health services and health outcomes.

DATA COLLECTION AND ANALYSIS

Two authors independently screened all potentially relevant records for inclusion criteria, extracted the data, and assessed the included studies' risk of bias. We requested missing information from the study authors.

MAIN RESULTS

Three studies (one cluster-RCT and two CBAs) comprising a total of 13,885 participants (9640 children and 4245 adults) as well as 1200 households in two LMICs (Nicaragua and Niger) met the inclusion criteria. They examined five UCTs between USD 145 and USD 250 (or more, depending on household characteristics) that were provided by governmental, non-governmental or research organisations during experiments or pilot programmes in response to droughts. Two studies examined the effectiveness of UCTs, and one study examined the relative effectiveness of in-hand UCTs compared with in-kind transfers and UCTs paid via mobile phone. Due to the methodologic limitations of the retrieved records, which carried a high risk of bias and very serious indirectness, we considered the body of evidence to be of very low overall quality and thus very uncertain across all outcomes.Depending on the specific health services use and health outcomes examined, the included studies either reported no evidence that UCTs had impacted the outcome, or they reported that UCTs improved the outcome. No single outcome was reported by more than one study. There was a very small increase in the proportion of children who received vitamin or iron supplements (mean difference (MD) 0.10 standard deviations (SDs), 95% confidence interval (CI) 0.06 to 0.14) and on the child's home environment, as well as clinically meaningful, very large reductions in the chance of child death (hazard ratio (HR) 0.26, 95% CI 0.10 to 0.66) and the incidence of severe acute malnutrition (HR 0.44, 95% CI 0.24 to 0.80). There was also a moderate reduction in the number of days children spent sick in bed (MD - 0.36 SDs, 95% CI - 0.62 to - 0.10). There was no evidence for any effect on the proportion of children receiving deworming drugs, height for age among children, adults' level of depression, or the quality of parenting behaviour. No adverse effects were identified. The included comparisons did not examine several important outcomes, including food security and equity impacts.With regard to the relative effectiveness of UCTs compared with a food transfer providing a relatively high total caloric value, there was no evidence that a UCT had any effect on the chance of child death (HR 2.27, 95% CI 0.69 to 7.44) or severe acute malnutrition (HR 1.15, 95% CI 0.67 to 1.99). A UCT paid in-hand led to a clinically meaningful, moderate increase in the household dietary diversity score, compared with the same UCT paid via mobile phone (difference-in-differences estimator 0.43 scores, 95% CI 0.06 to 0.80), but there was no evidence for an effect on social determinants of health, health service expenditure, or local markets and infrastructure.

AUTHORS' CONCLUSIONS

Additional high-quality evidence (especially RCTs of humanitarian disaster contexts other than droughts) is required to reach clear conclusions regarding the effectiveness and relative effectiveness of UCTs for improving health services use and health outcomes in humanitarian disasters in LMICs.

Trends in educational inequalities in cause specific mortality in Norway from 1960 to 2010: a turning point for educational inequalities in cause specific mortality of Norwegian men after the millennium?

Background

Educational inequalities in total mortality in Norway have widened during 1960–2000. We wanted to investigate if inequalities have continued to increase in the post millennium decade, and which causes of deaths were the main drivers.

Methods

All deaths (total and cause specific) in the adult Norwegian population aged 45–74 years over five decades, until 2010 were included; in all 708,449 deaths and over 62 million person years. Two indices of inequalities were used to measure inequality and changes in inequalities over time, on the relative scale (Relative Index of Inequality, RII) and on the absolute scale (Slope Index of Inequality, SII).

Results

Relative inequalities in total mortality increased over the five decades in both genders. Among men absolute inequalities stabilized during 2000–2010, after steady, significant increases each decade back to the 1960s, while in women, absolute inequalities continued to increase significantly during the last decade. The stabilization in absolute inequalities among men in the last decade was mostly due to a fall in inequalities in cardiovascular disease (CVD) mortality and lung cancer and respiratory disease mortality. Still, in this last decade, the absolute inequalities in cause-specific mortality among men were mostly due to cardiovascular diseases (CVD) (34% of total mortality inequality), lung cancer and respiratory diseases (21%). Among women the absolute inequalities in mortality were mostly due to lung cancer and chronic lower respiratory tract diseases (30%) and CVD (27%).

Conclusions

In men, absolute inequalities in mortality have stopped increasing, seemingly due to reduction in inequalities in CVD mortality. Absolute inequality in mortality continues to widen among women, mostly due to death from lung cancer and chronic lung disease. Relative educational inequalities in mortality are still on the rise for Norwegian men and women.

In-work tax credits for families and their impact on health status in adults

BACKGROUND

By improving two social determinants of health (poverty and unemployment) in low- and middle-income families on or at risk of welfare, in-work tax credit for families (IWTC) interventions could impact health status and outcomes in adults.

OBJECTIVES

To assess the effects of IWTCs on health outcomes in working-age adults (18 to 64 years).

SEARCH METHODS

We searched 16 electronic academic databases, including the Cochrane Public Health Group Specialised Register, Cochrane Database of Systematic Reviews (The Cochrane Library 2012, Issue 7), MEDLINE and EMBASE, as well as six grey literature databases between July and September 2012 for records published between January 1980 and July 2012. We also searched key organisational websites, handsearched reference lists of included records and relevant journals, and contacted academic experts.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials and cohort, controlled before-and-after (CBA) and interrupted time series (ITS) studies of IWTCs in working-age adults. Included primary outcomes were: self rated general health; mental health/psychological distress; mental illness; overweight/obesity; alcohol use and tobacco use.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias in included studies. We contacted study authors to obtain missing information.

MAIN RESULTS

Five studies (one CBA and four ITS) comprising a total of 5,677,383 participants (all women) fulfilled the inclusion criteria and were synthesised narratively. The in-work tax credit intervention assessed in all included studies is the permanent Earned Income Tax Credit in the United States, established in 1975. This intervention distributed nearly USD 62 billion to over 27 million individuals in 2011, and its administration costs were less than one per cent of its total costs. All included studies carried a high risk of bias (especially from confounding and insufficient control for underlying time trends). Due to the small number of (observational) studies and their high risk of bias, we judged this body of evidence to have very low overall quality.One study found that IWTC had no detectable effect on self rated general health and mental health/psychological distress five years after its implementation (i.e. a considerable change in the generosity of the permanent IWTC) and on overweight/obesity eight years after implementation. One study found no effect of IWTC on tobacco use five years after implementation, one a moderate reduction in tobacco use one year after implementation (odds ratio 0.95, 95% confidence interval (CI) 0.94 to 0.96), and one differential effects, with no effect in African-Americans and a large reduction in European-Americans two years after implementation (risk difference -11.1%, 95% CI -20.9% to -1.3%). No evidence was available for the effect of IWTC on mental illness and alcohol use. No adverse effects of IWTC were identified.One study also found no detectable effect of IWTC on the number of bad physical health days and of risky biomarkers for inflammation, cardiovascular disease and metabolic conditions eight years after implementation. One study found that IWTC had a large, positive effect on income from wages or salaries one year after implementation. Two studies found no effect on employment two and five years after implementation, whereas two found a moderate increase five and eight years after implementation and one a large increase in employment due to IWTC one year after implementation.No differences in outcomes between groups with different educational status were found for self rated health and mental health/psychological distress. In one study European-American women with lower levels of education were more likely to reduce tobacco use, while tobacco use did not change among African-American women with lower levels of education. However, no differences in tobacco use by educational status were observed in a second study. Two studies found that the intervention may have reduced inequity with respect to employment, where women with less education were more likely to move into employment (although one did not establish whether this difference was statistically significant), while two studies found no such difference and no studies found differences by ethnic group on employment rates.

AUTHORS' CONCLUSIONS

In summary, the small and methodologically limited existing body of evidence with a high risk of bias provides no evidence for an effect of in-work tax credit for families interventions on health status (except for mixed evidence for tobacco smoking) in adults.