Table 2.

Descriptive summaries of the 17 included studies, including quality appraisal (high quality/moderate quality/low quality)

No.	First author (year) and country	Sample size and age of the participants	Participant group	Intervention description	Type of research, data collection and analysis	Findings of the paper relevant to the review	Quality appraisal/ ROB
1	Beaton and Freeman25 (2016) UK	n=20, age not mentioned	Health and social care workers	Motivational interviewing to promote oral health among homeless populations (‘Smile4life programme’)	Qualitative— telephone interviews, framework approach	Familiarity and good relationships between service providers and third sector organisations facilitated implementation, whereas lack of resources and interest hindered it	High quality
2	Beaton et al26 (2018) UK	n=9 observation sessions, age not mentioned	Oral healthcare workers such as oral health educators and dental support workers	Motivational interviewing and tailored advice to promote oral health among the homeless population at different settings such as mobile dental units and homeless shelters (‘Smile4Life programme’)	Qualitative— participant observation, content analysis	Good working relationships between healthcare providers, patients and third sector organisations are important	Moderate quality
3	Beaton et al27 (2021) UK	n=100, 16–85 years	Oral health practitioners, third sector organisation staff and local authority staff	Motivational interviewing and behavioural change techniques to promote oral health among the homeless (‘Smile4Life programme’)	Quantitative— questionnaire, K-R20, exploratory factor analysis, multivariate path analysis	Work practices such as positive attitudes and beliefs of the oral healthcare workers influence implementation	Moderate quality
4	Burnam et al34 (1995) USA	n=276, mean age=37 years	Homeless individuals with co-occurring substance and mental health issues	Social model of residential and non-residential programmes providing integrated substance use and mental health services	Quantitative— structured interviews, regression analyses	Retention levels were higher in the residential programme compared with the non-residential one	Low quality
5	Coles et al29 (2013) UK	n=14, age not mentioned	Healthcare workers from statutory and non-statutory organisations	A framework that offers tailored oral health advice and signposts to relevant dental services. (‘Something To Smile About’)	Qualitative— focus groups, content analysis	Oral health knowledge among the healthcare workers improved but complex needs such as housing, employment, etc, must be addressed prior to oral health for successful implementation	Moderate quality
6	Collins et al35 (2019) USA	n=168, mean age=47 years	Homeless individuals with alcohol use disorder	Non-abstinence treatment programme that involves tracking of alcohol use, discussion of safe drinking practices and goal-oriented tasks (‘Harm Reduction Treatment for Alcohol HaRT-A’)	Quantitative—questionnaires, content analysis	It was positively viewed by the participants with high levels of retention and satisfaction	High quality
7	Doughty et al31 (2020) UK	Service users— n=353, age not mentioned Service providers—not stated	Homeless individuals and oral healthcare workers such as dentists, dental nurses, dental technicians, etc	Denture service provided by Crisis at Christmas Dental Service and Den-tech to the homeless and vulnerably housed	Qualitative	Communication, timing, resources and training were considered as areas that needed to be improved	Low quality
8	Forchuk et al36 (2022) Canada	Service users— n=58, mean age=52.5 years Service providers— not stated	Homeless veterans with substance use problems and staff from housing services	Housing provided along with the peer support and harm reduction services to homeless veterans (‘Housing First’)	Qualitative— interviews and focus groups, thematic analysis	Stable housing with harm reduction services was well received. Collaboration between mental health and addiction services should be considered for future services	Low quality
9	Henderson37 (2004) USA	Service users— n=15 Service providers— not mentioned	Homeless veterans with substance/alcohol use and programme staff such as healthcare workers and administrative staff	Residential substance use treatment programme that focuses on relapse prevention along with education and housing stability for homeless men	Qualitative— surveys, direct observation and interviews, not stated	Majority of the participants provided positive feedback. Staffing issues such as training and competing workload were noted as drawbacks to the programme	Moderate quality
10	Neale and Stevenson33 (2014) UK	Service users— n=30, 23–62 years Service providers— n=15, age not mentioned	Homeless individuals with substance use and mentors such as substance use workers, substance use managers and hostel staff	Computer-assisted therapies using 20 different psychosocial intervention strategies to identify and reduce substance use based in hostels and homeless shelters (‘Breaking Free Online’)	Qualitative— interviews, inductive coding and framework approach	‘Programme features’, ‘mentor support’, ‘participant characteristics’ and ‘delivery context’ were noted as factors that lead to successful delivery	Moderate quality
11	Paisi et al32 (2020) UK	Service users— n=11, 20–65 years Service providers— n=11, age not mentioned	Homeless individuals and the dental clinic staff members, support workers and volunteers	Community dental clinic that provides both regular and emergency treatments	Qualitative— semistructured interviews, reflective thematic analysis	Flexibility and the relationship between the patient and dental provider were highlighted as important features	High quality
12	Pauly et al38 (2020) Canada	n=14, 29–61 years	Homeless with illicit alcohol use	Non-residential community managed alcohol programme which provides harm reduction strategies and peer support (‘Canadian Managed Alcohol Programme Study’)	Qualitative— semistructured interviews, inductive coding and constant comparative analysis	Peer-led programme was successful as it facilitates capacity building, engagement, and empowerment	Moderate quality
13	Pratt et al40 (2019) USA	n=40, 29–69 years	Homeless with smoking and alcohol use	Nicotine replacement therapy and motivational interviewing/cognitive behavioural therapy to reduce smoking and alcohol use among the homeless (‘Power To Quit 2’)	Qualitative— interviews, social constructivist approach to grounded theory	Social (peer groups) and environmental (housing, etc) factors impact cessation in homeless smokers	High quality
14	Pratt et al41 (2022) USA	n=40, 29–70 years	Homeless with smoking and alcohol use	Nicotine replacement therapy and motivational interviewing/cognitive behavioural therapy to reduce smoking and alcohol use among the homeless (‘Power To Quit 2’)	Qualitative—semistructured interviews, social constructivist approach to grounded theory	Social pressure and shelter environment impact the intervention but the integrated treatment along with emotional support from the staff make it beneficial	High quality
15	Rash et al39 (2017) USA	n=355, mean age=37 years	Homeless with substance use	Behavioural intervention contingency management with the use of incentives such as vouchers and prizes delivered at local community clinics	Quantitative—adaptation of the Service Utilisation Form, multivariate analysis of variance	Retention was higher in groups that accessed the intervention compared with the standard arm of care	Moderate quality
16	Rodriguez et al28 (2019) UK	Service users— n=13, 18–22 years Service providers— n=5, age not mentioned	Young homeless people and NGO practitioners	Pedagogical workshops about oral health, mental health, substance misuse, diet, etc, to increase engagement and awareness	Qualitative— unstructured interviews and workshops, content analysis	Involvement of young people in co-designing an intervention facilitates engagement, trust building and increases health literacy	High quality
17	Stormon et al30 (2018) Australia	n=76, 41–60 years Feedback— n=24	Disadvantaged adults (clients of community organisations that use housing, employment and food services)	Facilitated access pathway between homeless organisations and public dental services. Improving oral health by assessing dental needs, offering dental advice and dental appointments	Quantitative—questionnaire, descriptive analysis, and framework approach	Positive feedback by participants facilitated by the environment, clinical staff and flexibility. Attendance rates varied across the site but was generally high.	Moderate quality

ROB, risk of bias.