Within the neighborhood theme, a better neighborhood environment (linked to aspects like access to green spaces and upkeep of buildings), attractiveness, and safety had a positive association with residents' psychological well-being. Similar positive associations were observed in studies exploring the role of social networks and neighborhood reputation, particularly concerning levels of deprivation and wealth. The impact of housing location on residents' well-being was explored in the included studies, finding a more positive association between residents' well-being and living in rural rather than urban areas, and mixed evidence on the effects of living close to urban amenities, which could be seen as either convenient or stressful.

Different factors were explored under the building theme. Poor housing conditions were found to be negatively associated with mental well-being, in particular when housing repair and housing improvement were taken into consideration. Certain housing features were linked to positive associations with residents' health and quality of life such as: having new window and door fixtures (e.g., associated with improved sense of safety), smoke detectors (e.g., associated with lower risk of death and disability), internet access (e.g., associated with improved mental well-being), and insulation (e.g., associated with better thermal comfort and reduced risk of developing illnesses like asthma or bronchitis). Furthermore, living in houses built with brick veneer was found to be related to lower levels of temperature variations, while living in older houses was associated with having poorer insulation and air conditioning systems. The housing type, size, and dwelling appeared to matter too, as studies found that people living in detached houses, larger accommodations, or houses a with low number of occupants had better perceived health and mental well-being, and life satisfaction.

In the policy section, this review evaluated the health impacts of homeownership and house stability. Homeownership (compared to being a tenant) was associated with lower stress levels, better social and economic outcomes, and mental health outcomes, although these associations were weaker for people who had mortgages. The relationship between homeownership and self-esteem was found to be negative. The evidence regarding house-related subjective well-being was inconclusive, with some studies pointing to a positive effect with homeownership, while some found no association. In the case of divorce, owning a house was found to be a negative contributing factor to subjective well-being, as it would become a financial burden.

Additionally, older populations and children's health needs were found to be lower for those living in their own house. In the case of children, living continuously in a rented property was associated with negative behaviors such as aggressiveness. House stability was associated with life satisfaction, mental well-being, and physical health. Insecure housing was found to be a factor of stress that could have long-term implications. In cases of relocation due to regeneration policies, impacts such as poorer mental health and well-being, damaged sense of community, feeling of loss of control, and general unhappiness were found. Negative mental health effects from housing mobility tend to be stronger in later childhood, which consequently is associated with anxiety and depression among mothers.

Different financial factors linked to housing were considered within this theme. Living in less affordable housing was linked to poorer psychological and mental well-being. Some studies indicated that lower levels of income were associated with higher energy insecurity, potentially impacting on the residents' health. However, living in areas with higher housing costs was not found to be necessarily associated with impacts on well-being. Other factors, linked to labor market conditions, seemed to play more of a significant role. The housing market seemed to be associated with mixed impacts on residents' health, with rising houses' prices positively affecting homeowners' physical health but negatively impacting both physical and mental health of tenants.

We critically appraised the methods and reporting of the systematic review by Alidoust and Huang (2021) by using the Joanna Briggs Institute tool (10) (Table 1). Firstly, while the choice of the databases (Google Scholar and Scopus) to identify suitable studies may reflect the generic review question, with only two databases and only first 100 results being used it is possible that important studies were missed resulting in evidence selection bias (11, 12). Secondly, no details were reported on how the data extraction process was undertaken (again limiting any repeatability) nor on any formal critical appraisal of the studies included, whose quality remains uncertain. The sporadic and unsystematic reporting of statistical significance of the results also makes it difficult to weigh how each study contributes to answering the review's question. Moreover, no formal analysis of potential publication bias was attempted. As a result of this critical appraisal, we believe the work by Alidoust et al.¹ aligns more closely with a scoping review. This determination is drawn from the methods used, for example, the review restricted databases to only two, limited the inclusion studies based on publication year, and lack of quality assessment for the included studies (13). We highlight the need for transparency in titles and reporting to avoid potential confusion and contribute to a more accurate understanding of methodologies in evidence reviews.

We aimed to put the findings of the review by Alidoust et al.¹ in context to current policy and practice, as outlined below according to the specific housing-related theme.

Given the limitations we underlined on the systematic review by Alidoust et al¹, better focused systematic reviews, featuring a more clearly defined search strategy, a wider set of databases and more systematic screening and critical appraisal procedures are recommended in this domain of research. At the same time, given the breadth of the literature of housing impacts on health, it appears sensible to develop separate reviews (or sub-reviews) both on quantitative and qualitative evidence and on different populations. Secondly, 85% of studies in this review were quantitative suggesting a lack of included qualitative studies. This may be reflective of the topic area; however, one recommendation would be to use qualitative research methodologies to explore and synthesize people's lived experience of housing. This would provide an additional perspective to existing research, such as highlighting important outcomes that may have been overlooked, and providing deeper explanation to findings (39). Nonetheless, the comprehensive scope of this review can be instrumental in informing predictive models assessing the impact of housing and neighborhood factors on health. This, in turn, can aid in the design of improved living environments in the future. It should be noted that we draw our recommendations for policy and future research on the basis of our RaCES critical appraisal of one systematic review. Inevitably, the scope of our recommendations will be determined by the scope of the review and the quality of the findings by Alidoust et al.¹. As such, we recognize that a more systematic process of finding evidence-based recommendations (e.g., umbrella reviews) could represent an avenue for future research.

This commentary critically appraised the systematic review by Alidoust et al.¹ on the multiple impacts of housing on health. We identified limitations with the methods used in the systematic review regarding the use of databases, and the rigor and transparency of the processes related to screening, data extraction and quality assessment, which all indicate the need for further research in this area. We suggested implications for policy based on the review's findings, context of current policy, and other supportive literature. In particular, we highlight a range of evidence-based initiatives aiming to improve (i) neighborhood attractiveness, social networks, and internal reputation, (ii) building conditions, temperature, density, and materials (iii) housing affordability and tenancy conditions, and (iv) labor market attractiveness which all have the potential of enhancing physical and mental health.