As the quite diverse systems across countries make comparisons between studies difficult, it is hard to evaluate the literature for scientific evidence regarding housing adaptations and home modifications . The majority of published housing adaptation evaluations lack theory-based definitions of core concepts and outcomes. According to the Cochrane reports (Gillespie et al. 2003; Lyons et al. 2003), the scientific evidence of the effects of housing adaptations and home modifications is limited. Yet, according to a literature review, including studies with mainly older people (Wahl et al. 2009) there is substantial evidence of positive effects. Positive effects were indicated on (1) functional decline (Mann et al. 1999), (2) fear of falling (Cumming et al. 1999; Heywood 2004), (3) pain and depression (Heywood 2004), (4) satisfaction and performance in daily activities (Gitlin et al. 2001; Stark 2004), and (5) costs of healthcare and social services (Mann et al. 1999). Most recent studies on housing adaptations and home modifications show promising results (see e.g., Sheffield et al. 2013). However, regarding health economy outcomes, the scientific evidence is nonexistent (Chiatti and Iwarsson 2014).

Housing adaptations and home modifications should be recommended as interventions that support the maintenance of independence in activities of daily living (Wahl et al. 2009) and occupational performance in general (Fänge and Iwarsson 2007). Still, there are critical methodological challenges for practice and future ­research (Malmgren Fänge et al. 2013). As the quotation at the start of this chapter demonstrates, another challenge is to present scientific evidence that would make some individual housing adaptations unnecessary. Applying such a health promotion ­approach, and using experience and knowledge generated from individual housing adaptation cases to be translated into recommendations for housing provision as part of the process of planning a society for all (Ainsworth and de Jonge 2011; Iwarsson 2005), is a challenging but important avenue for future development.