Disability-free life expectancy is the estimate of how long an individual can expect to live in good health and without disability. Both men and women living in least deprived areas can expect to live nearly two decades longer in good health than people living in the most deprived areas.1UK Office for National StatisticsHealth state life expectancies by national deprivation deciles, England: 2016 to 2018.https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/healthinequalities/bulletins/healthstatelifeexpectanciesbyindexofmultipledeprivationimd/2016to2018Date: March 27, 2020Date accessed: July 27, 2021Google Scholar Socioeconomic inequalities in disability-free life expectancy continue to grow,2Bennett HQ Kingston A Spiers G et al.Healthy ageing for all? Comparisons of socioeconomic inequalities in health expectancies over two decades in the Cognitive Function and Ageing Studies I and II.Int J Epidemiol. 2021; 50: 841-851Crossref PubMed Google Scholar probably exacerbated by the COVID-19 pandemic. People living with disability are more likely to have poor health, worse quality of life, persistent barriers to education and employment, and greater socioeconomic deprivation than individuals without disabilities. The arguments for the need to reduce inequality in years lived free of disability are both moral and economic.3WHODisability and health.https://www.who.int/news-room/fact-sheets/detail/disability-and-healthDate: Nov 24, 2021Date accessed: February 21, 2022Google Scholar In this Comment, we explore how well the evidence base helps to narrow that gap. Taking three common conditions—depression, osteoarthritis, and type 2 diabetes—as an example, we searched for published evidence to assess how often interventions are evaluated in terms of their effects on different socioeconomic groups. Globally, one in three adults is estimated to live with multiple long-term conditions, and this prevalence is projected to increase.4Hajat C Stein E The global burden of multiple chronic conditions: a narrative review.Prev Med Rep. 2018; 12: 284-293Crossref PubMed Scopus (239) Google Scholar The greatest burden of long-term conditions is already known to fall on the most disadvantaged groups. People who are socioeconomically disadvantaged are at higher risk of developing long-term conditions earlier in life and with greater disease severity.5The King's FundLong-term conditions and multi-morbidity.https://www.kingsfund.org.uk/projects/time-think-differently/trends-disease-and-disability-long-term-conditions-multi-morbidityDate: 2021Date accessed: July 27, 2021Google Scholar Depression, osteoarthritis, and type 2 diabetes all make substantial contributions to population-level morbidity, disability, and mortality, and all show stark socioeconomic gradients.6Lourida I Bennett HQ Beyer F Kingston A Jagger C The impact of long-term conditions on disability-free life expectancy: a systematic review.PLoS Glob Public Health. 2022; 2e0000745Crossref Google Scholar In addition, these conditions vary in type of treatment, age profile of those affected, and in affecting mental or physical health. Our research supports a transparent platform from which to advance the priorities set in the UK Government's Levelling Up agenda, which aims to reduce the gap in healthy life expectancy by 2030.7UK Department for Levelling UpLevelling up the United Kingdom.https://www.gov.uk/government/publications/levelling-up-the-united-kingdomDate: Feb 2, 2022Date accessed: June 14, 2022Google Scholar The UK National Institute for Health and Care Excellence (NICE) sets key priorities to implement personalised care, tailored to individual needs. Evidence on widely implemented and effective interventions for these conditions has already been reviewed and distilled into recommendations by NICE. Effective interventions include high-intensity psychological or pharmacological interventions for depression;8UK National Institute for Health and Care ExcellenceDepression in adults: recognition and management (guidance).https://www.nice.org.uk/guidance/cg90Date: Oct 28, 2009Date accessed: February 3, 2022Google Scholar education and self-management and pharmacological or surgical interventions for osteoarthritis;9UK National Institute for Health and Care ExcellenceOsteoarthritis: care and management.https://www.nice.org.uk/guidance/cg177/resources/osteoarthritis-care-and-management-pdf-35109757272517Date: Feb 12, 2014Date accessed: July 27, 2021Google Scholar and education and self-management and non-pharmacological or pharmacological interventions for type 2 diabetes.10UK National Institute for Health and Care ExcellenceType 2 diabetes in adults: management.https://www.nice.org.uk/guidance/ng28Date: Dec 2, 2015Date accessed: July 29, 2021Google Scholar We found that, between Jan 3, 2008, and Jan 6, 2022, 8636 studies reporting evaluations of these NICE-recommended interventions for depression (2744 reviews), osteoarthritis (5137 primary studies), and type 2 diabetes (755 reviews) were published. Evidence about whether these interventions are successful in managing these long-term conditions is not in short supply. However, a closer examination of this evidence reveals a crucial shortcoming: only 19 (0·22%) of these 8636 publications considered the outcomes of the intervention by socioeconomic status (seven reviews in depression and 12 primary studies in osteoarthritis). In short, more than a decade's worth of publicly funded research has rarely considered whether interventions can produce equal outcomes across different socioeconomic circumstances, or whether they reduce the existing gaps in outcomes. In addition, our targeted searches using a systematic review methodology also found scarce evidence for socioeconomic patterning in outcomes for interventions in depression and osteoarthritis and no evidence at all for type 2 diabetes. The scarce available evidence varied (in study design, populations, comparable measures of socioeconomics, and outcomes), but tended to show better outcomes for less disadvantaged people, particularly those with high levels of education and income (table).TableAssociation between socioeconomic status and clinical outcomes by intervention, from two examples of long-term conditionsSocioeconomic measureSummary of findingsDepressionSchool-based cognitive behavioural therapyLow and high socioeconomic statusCould favour children from middle and high socioeconomic backgrounds, although the evidence was contrasting in a review of studies with greater risk of biasCommunity or mobile cognitive behavioural therapyLevel of educationNo evidence of differential effect between groupsInternet-guided cognitive behavioural therapyEmployment statusCould offer worse outcomes for unemployed people, compared with usual careOsteoarthritisEducation and self-managementLevel of education; employment status; birthplaceFavoured more advantaged populations; could favour advantaged population in the short-termPharmacologicalSocioeconomic statusNo evidence of differential effect between groupsSurgicalPlace of residence; employment status; level of education; incomeNo evidence of differential effect between groups; could offer better outcomes for those with higher levels of education; could offer worse outcomes for those with lower income Open table in a new tab Our analysis has identified an important gap in the evidence needed to inform policy on narrowing the gap in disability-free life expectancy between socioeconomically advantaged and disadvantaged individuals, with a dearth of research on how the effects of interventions for long-term conditions vary for people living in different socioeconomic circumstances. Although our analysis is focused on the UK's health context, the evidence is drawn from the highest quality research globally. Our conclusions are therefore likely to have international relevance, especially as other countries contend with widening economic inequalities. To target interventions or evaluate the effect of policies and interventions on disadvantaged groups, measurement and reporting of socioeconomic status and its impact on the effects of interventions must become the norm. We declare no competing interests.