Table 1 Provides a summary of the characteristics of the studies included in this review

Characteristics of participants, where reported in studies

Median no. of participants

2579

Median % male

65

Median age of participants

43.7

Year of study

 2010 – 2012

3 (10.0)

[27, 33, 36]

 2013 – 2014

3 (10.0)

[30, 34, 37]

 2015 – 2016

2 (7.0)

[26, 41]

 2017 – 2018

4 (14.0)

[23, 47, 48, 50]

 2019 – 2020

10 (33.0)

[22, 25, 28, 31, 32, 39, 43, 46, 49, 51]

 2021

8 (28.0)

[24, 29, 35, 38, 40, 42, 44, 45]

Country

 United States

14 (47.0)

[22,23,24,25,26,27,28,29,30,31,32,33,34,35]

 United Kingdom

3 (10.0)

[43,44,45]

 Canada

7 (23.0)

[36,37,38,39,40,41,42]

 Australia

2 (7.0)

[48, 49]

 Denmark

2 (7.0)

[46, 47]

 Ireland

2 (7.0)

[50, 51]

Time horizon

 1 year or less

7 (23.0)

[24, 26, 28, 30, 40, 41, 50]

 2—3 years

5 (17.0)

[22, 32, 43, 44, 48]

 4—5 years

8 (27.0)

[34, 36, 37, 39, 42, 45, 46, 51]

 5 + years

10 (33.0)

[23, 25, 27, 29, 31, 33, 35, 38, 47, 49]

Focus area

 Mortality, morbidity and COVID-19

7 (23.3)

[23, 27, 33, 40, 43, 46, 49]

 Healthcare utilisation

12 (40.0)

[22, 24,25,26, 29, 34, 36, 37, 39, 42, 45, 50]

 Care home admission and shelter usage

3 (10.0)

[35, 38, 51]

 Hospital re-admission

6 (20.0)

[28, 30,31,32, 41, 44]

 Other (employment rates and police crime victimisation)

2 (6.7)

[47, 48]

Number of linked data sources used

 Less than 2

17 (57.0)

[25,26,27,28,29,30, 32, 34, 35, 38, 39, 41, 45, 48, 49, 51]

 3 to 5

10 (33.0)

[23, 31, 33, 36, 37, 43, 44, 46, 47, 50]

 Greater than 5

3 (10.0)

[24, 40, 42]

Data linkage method

 Deterministic linkage (using an unique identifier, such as a social security number)

22 (73.0)

[25,26,27,28, 31, 32, 34,35,36,37,38, 40,41,42,43,44,45, 47, 49,50,51]

 Fuzzy / Probabilistic linkage (linking by people's names etc.)

4 (13.0)

[29, 30, 33, 48]

 Deterministic and Probabilistic

4 (13.0)

[22,23,24, 39]

Software

 SPSS

5 (17.0)

[22, 36, 45, 50, 51]

 STATA

3 (10.0)

[23, 26, 28]

 R

2 (7.0)

[35, 44]

 SAS

13 (43.0)

[24, 25, 29,30,31,32,33,34, 37, 40,41,42, 47]

 Stata and R

1 (3.0)

[43]

 SPSS and Stata

1 (3.0)

[49]

 SAS and R

1 (3.0)

[39]

 Not reported

4 (13.0)

[27, 38, 46, 48]

Source of funding

 Public grants (including government)

20 (67.0)

[23, 25, 33,34,35,36,37,38, 40, 42,43,44,45,46,47,48, 50]

 University grants

2 (7.0)

[28, 29]

 not stated

8 (27.0)

[22, 26, 27, 30, 32, 38, 49, 51]