Table 2.

Summary of the population, area of HIV and interventions considered per study included

Reference and country of origin	Population (number and inclusion criteria)	Area of HIV continuum	Intervention and comparator	Overall article quality
Randomised controlled trial
Choko et al. (2019)[18]	Population: Male partners of pregnant women who had their first prenatal visit. 1: 1 ratio in all 5 groups were considered, obtaining a total sample of 2,349 individuals	Prevention: male circumcision rate	Intervention: 4 incentive strategies, 3 with financial incentives (assignment of rapid HIV tests with $ 3 and $ 10 conditional fixed incentives and a third incentive based on a $30 lottery) and a strategy with non-financial incentives (quick test + two calls follow-up phone calls)	High
Country of origin: Malawi	Inclusion: pregnant women who had their first prenatal care appointment	Link to treatment care	Comparator: clinical practice with no financial incentives
El-Sadr et al. (2019)	Population and Inclusion: Participants in the HPTN 065 study (El-Sadr et al. 2017)	Care retention (continuity of care)	Intervention: utilisation of individual financial incentives around continuity of care (e.g. attending appointments) and viral suppression	High
Country of origin: USA		Viral load suppression	Comparator: clinical practice with no financial incentives
Thirumurthy et al. (2019)	Population: 400 participants (203 in the intervention group and 197 in the control group)	Care retention	Intervention: received financial incentives conditional for viral suppression at 6, 12 and 24 weeks, with the value of the incentive to scale from $ 4 to $ 12.5	Intermediate
Country of origin: Uganda	Inclusion: aged 18 + , living in one of the four communities considered in the study, with a positive result for HIV, and who were starting or already receiving ART	Adherence to treatment and viral suppression	Comparator: viral load tests and counselling
Kadota et al. (2018)	Population: 805 HIV positive individuals recruited at 3 clinics	Link to care and ART initiation	Intervention: two intervention groups:(1) food assistance; (2) money transfers	High
Country of origin: Tanzania	Inclusion: Adult HIV patients, with food insecurity, and on ART initiation ≤ 90 days before enrolment in the study	Care retention	Comparator: usual care
Maughan-Brown et al. (2018)	Population: 84 individuals equally distributed between groups	Link to care and ART initiation	Intervention: usual care + voucher (exchangable for monetary value if ART started in the following 3 months)	Intermediate
Country of origin: South Africa	Inclusion: HIV-diagnosed adults referred for ART by a mobile health clinic in Cape Town who had never previously had ART		Comparator: usual care (telephone follow-up advice from staff to encourage care promotion)
Mills et al. (2018)	Population: Participants from two rural districts of Uganda, recruited through AIDS centres and home visits to patients who had not visited a centre recently	Prevention	Intervention: unconditional monetary grants, with or without financial advice: Group T1: unstructured grant; Group T2: mental planning + grant	Intermediate
Country of origin: Uganda	Inclusion: HIV positive, aged between 18 and 60 years old, living in the two rural districts considered	Link to care and ART initiation
		Viral suppression	Comparator: Group T3: control (no incentives); and Group T4: expectations / control (participants were told they would receive a monetary grant 12 months after the program started—after the follow-up interview)
Montoy et al. (2018)	Population: 8,715 patients in an urban emergency department (San Francisco)	Testing and screening	Intervention: $ 1 incentives, $ 5 incentives, or $ 10 incentives (each of these groups, with 3 subgroups—opt-in, active choice, opt out test)	High
Country of origin: USA	Inclusion: aged between 13–64 years; being able to give consent for HIV testing and study inclusion in the study; speak English or Spanish		Comparator: without incentives (also with 3 subgroups—opt-in, active choice, opt out test)
Chamie et al. (2018)	Population: A total of 2,527 participants had complete data and were considered for analysis	Testing and screening	Intervention: (1) incentives included in the loss: participants who had won a prize were later told they would lose that prize if they did not take the test; 2) lottery-based incentives: participants who had an HIV testing automatically enter a lottery and had the opportunity to instantly win prizes	High
Country of origin: Uganda	Inclusion: adult men (≥ 18 years old) referred to in the censuses, who lived in the community for ≥ 6 months in the year prior to referral and who had no intention of leaving the community in the following 3 months
Alsan et al. (2017)	Population: 110 HIV-infected adults with a plasma viral load (pVL) > 200 copies / mL despite ART (n = 21 adults in the professional visit incentive group; n = 19 adults in the choice incentive group, n = 70 in the passive control group)	Care retention and adherence to treatment	Intervention: (1) incentive group to visit professionals (US $30 incentive after participating in each scheduled visit to professionals); (2) incentive choice group (commitment contract that makes the payment of US $ 30 conditioned both to participation in the scheduled visits of professionals and adherence to ART)	Intermediate
Country of origin: USA	Inclusion: the HIV-1 plasma RNA viral load over > 200 copies / mL measured in the previous 18 months and at least 6 months after starting the current ART regimen	Viral suppression	Comparator: routine care without any incentive
El-Sadr et al. (2017)	Population: 1,159 HIV patients (new HIV patients or unknown to healthcare in the past 12 months) were recruited to assess adherence to healthcare (389 in New York and 770 in Washington) and a total of 16,208 patients with HIV (established HIV patients) were recruited to assess viral load suppresion (9,703 in New York and 6,505 in Washington)	Care retention and adherence to treatment	Intervention: healthcare providers were randomised to provide financial incentives to HIV patients. Participants received: (1) a $ 125 voucher ($ 25 for conducting CD4 tests and $ 100 for an HIV planning medical consultation); and / or (2) $ 70 voucher for HIV testing with suppressed viral load (CD4 < 400 copies / mL), with a maximum of one voucher each quarter	High
Country of origin: USA	Inclusion: Health providers, not their users, were randomised to the intervention and control group	Viral suppression	Comparator: healthcare providers randomised not to give financial incentives (i.e. follow usual care)
Stitzer et al. (2017)	Population: post hoc secondary analysis of the HOPE study (Metsch et al., 2016)	Care retention	Intervention: please refer to Metsch et al. (2016) – see below	Intermediate
Country of origin: USA	Inclusion: please refer to Metsch et al. (2016) – see below		Comparator: please refer to Metsch et al. (2016) – see below
Metsch et al. (2016)	Population: 801 patients with HIV and substance abuse from 11 hospitals	Viral suppression	Intervention: 2 groups: (1) received a structured patient navigation intervention (up to 11 care coordination sessions, with case management and motivational interview techniques over 6 months) (n = 266); (2) structured patient navigation intervention and financial incentives (up to US $ 1,160) (n = 271)	High
Country of origin: USA	Inclusion: several criteria are mentioned (e.g. inpatients with HIV infection, being 18 years or older)		Comparator: usual care (n = 264)
de Walque et al. (2015)	Population: HIV patients from different clinics randomised to the intervention and control group	Testing and prevention	Intervention: randomised health care providers (n = 10) received incentives in the field of HIV prevention and treatment (organisational incentive)	Intermediate
Country of origin: Rwanda	Inclusion: Health care providers that treat patients with HIV infection were randomised		Comparator: randomised health care providers to receive an increase in fixed financing equivalent in magnitude to the intervention model (n = 14)
de Walque et al. (2012)	Population: 2,399 participants between the ages of 18 and 30 from certain ten geographical areas in Tanzania	Prevention	Intervention: two groups, with varying magnitude of incentive: (1) group with low level of incentive ($ 30 total incentive) and (2) group with high level of incentive ($ 60 total incentive). In both cases, the incentive was conditional on a negative test result every 4 months	Intermediate
Country of origin: Tanzania			Comparator: usual care with no incentives
Barnett et al. (2009)	Population: 86 individuals, with 66 of these with less than 80% adherence to their ART (34 were allocated to the incentive group with a voucher and 32 were allocated to the comparison group)	Care retention and adherence to treatment	Intervention: incentives with vouchers conditional on adherence to ART. The participant could accumulate earnings before choosing a redeemable voucher for purchases, meals or other	Intermediate
Country of origin: USA	Inclusion: HIV positive patients on methadone maintenance were eligible if they had been taking ART for at least 1 month		Comparator: weekly lottery was used to reduce dropouts among these participants, (3 in 1 chance of winning a small prize and a 350 in 1 chance of winning $80)
Non-randomised prospective study
Belenky et al. (2018)	Population: a total of 801 women with HIV and different insurance coverage	ART initiation	Intervention: change to the HIV drug financing model: HIV patients with Medicare / Medicaid double coverage, eligible for the transition to the Medicare Part D system in Jan 2006	High
Country of origin: USA	Inclusion: women with HIV with at least one HIV follow-up visit; and included in the Medicare / Medicaid program (double coverage) or only in the Medicaid program with adherence to the Medicare Part D program in January 2006	Viral suppresion	Comparator: HIV patients and Medicaid coverage and no additional insurance in 2005
Brantley et al. (2018)	Population: HIV patients recruited from 3 clinics in the State of Louisiana in the USA (n = 2076)	Adherence to ART	Intervention: assigning multiple individual card incentives: an initial incentive of $ 50, $ 20 for each medical consultation, $ 10 for each laboratory exam, $ 10 for referral to the service and $ 75 for keeping the viral load below the target (n = 2076)	Intermediate
Country of origin: USA	Inclusion: HIV patients with at least one laboratory test in the year prior to recruitment	Viral suppresion	Comparator: HIV patients who did not integrate the individual incentive model
Rajkotia et al. (2017)	Population: 134 health institutions	Prevention	Intervention: organisational incentive model based on performance-based unit payments	High
Country of origin: Mozambique	Inclusion: health institutions in the provinces of Nampula (north) and Gaza (south), certified by the Government of Mozambique to provide ART and prevention of mother-to-child transmission of HIV		Comparator: only standard input-based financing (without performance-based incentives)
Foster et al. (2014)	Population: A total of 11 adults with an average age of 19 years and 8 months	Viral load suppresion	Intervention: allocation of individual financial incentives in combination with consultation with a clinical psychologist and / or specialist nurse trained in motivational interviewing techniques (up to a total incentive of £ 200 conditional on sustained reductions in viral load and participation in motivational consultation)	Low
Country of origin: UK	Inclusion: patients with vertically acquired HIV who transitioned from paediatric services to adults with: CD4 count < 200 cells / µL); not taking ART despite several attempts to start treatment; and with the intention of resuming ART		Comparator: no comparator / control group
Modelling studies (cost-effectiveness studies)
Wagner et al. (2020)	Population: Patients in the emergency department of the Zuckerberg San Francisco General Hospital and Trauma Centre (Montoy et al., 2015)	Prevention	Intervention: small immediate financial incentives, opt-in / opt-out testing and a combination of both schemes	Intermediate
Country of origin: USA	Inclusion: age between 13–64 years; being able to give consent for HIV testing and the study; speak English or Spanish. Patients with previous HIV diagnosis were excluded	Testing and screening	Comparator: standard option (offering tests through an inclusion or exclusion regime)
Adamson et al. (2019)	Population: HIV patients in the Bronx (New York) and Washington DC (n = 16.208)	Viral load suppression	Intervention: $ 70 vouchers for patients with CD4 viral load < 400 copies / mL	High
Country of origin: USA	Inclusion: HIV patients who received incentives based on a randomised clinical trial (El-Sadr et al. 2017)		Comparator: no comparator / control group was considered
Stevens et al. (2018)	Population: participants in the Link4Health randomised clinical trial	Prevention	Intervention: (1) Point-of-care CD4 + count testing; (2) Accelerated ART initiation; (3) Mobile phone appointment reminders; (4) Care and prevention package including commodities and informational materials; and (5) Non-cash financial incentive	High
Country of origin: Swaziland		Testing and screening	Comparator: usual care with no incentive
Heymer et al. (2012)	Population: Based on HIV epidemiology in South Australia (data from 2004 to 2008)	Prevention	Intervention: removal of negative financial incentive (co-payment)	High
Country of origin: Australia	Inclusion: not mentioned		Comparator: usual care with co-payments