Eligible Studies
A total of 1,621 records were identified in the search. After the removal of duplicates (n = 487), 1134 articles remained and underwent screening based on title and abstract. This first level of screening led to the exclusion of 1,014 articles. A total of 120 articles were assessed for eligibility through full-text screening and 12 studies met the inclusion criteria for the review (See Figure 1 for PRISMA flow diagram). A list of studies that were excluded upon full-text review, including the reason(s) for their exclusion, are provided in Additional file 2.
Study Characteristics
Characteristics of the included studies are provided in Table 1. All studies were published between 1994 and 2019. Nearly half of the studies were conducted in Spain (n = 5; 42%). Other countries represented were Netherlands (n = 2; 17%), Poland (n = 2; 17%), Brazil (n = 1; 8%), Greece (n = 1; 8%), Uruguay (n = 1; 8%). None of the included studies were conducted in North America.
Table 1. Information for included studies.
|
First Author, Year (Ref)
|
Data Collection (Total Years)
|
Deceased Donation Outcomes Reported
(Units)
|
|
|
Potential Donors
|
Actual Donors
|
Consent Rate
|
Organ Procurement
|
Organ Transplants
|
Conversion Rate
|
Cohort Studies
|
Netherlands
|
(Vorstius Kruijff, 2016) (14)
|
01/2014 — 12/2014 (1)
|
|
|
%
|
|
|
|
(Witjes, 2019) (16)
|
01/2013 – 06/2016 (4)
|
|
|
%
|
|
|
|
Spain
|
(Domínguez-Gil, 2017) (21)
|
11/01/2014 — 04/30/2015 (1)
|
|
|
%
|
|
|
|
Interrupted Time Series Studies
|
Brazil
|
(Sarlo, 2015) (23)
|
2011 – 2014 (4)
|
N
|
N
|
|
|
|
%
|
Greece
|
(Karatzas, 2007) (22)
|
2001 – 2005 (5)
|
N
|
N
|
|
|
N
|
|
Spain
|
(Matesanz, 1994a)a (25)
|
1989 – 1992 (4)
|
|
pmp
|
|
%
|
|
|
(Matesanz, 1994b)a (24)
|
1989 – 1992 (4)
|
|
pmp
|
|
pmp/%d
|
pmp
|
|
(Miranda, 2001)a (15)
|
1990 – 2000 (11)
|
pmp
|
|
%b
|
|
|
|
Uruguay
|
(Mizraji, 2007) (17)
|
2000 – 2005 (6)
|
N/pmp
|
N/pmp
|
%b
|
|
|
|
Before-and-After Studies
|
Poland
|
(Czerwiński, 2014) (19)
|
~ 2011 – 2014 (3.5)
|
N
|
N
|
%b
|
%d
|
N/per donor
|
% of PDc
|
(Sikora, 2014) (18)
|
? – 06/2012 (>1.5)
|
N
|
N
|
%b
|
|
|
% of PDc
|
Spain
|
(Santiago, 2005) (20)
|
Not specified
(> 6)
|
%
|
pmp
|
%b
|
per donor
|
per donor
|
% of AD
|
Note. AD = actual donors; PD = potential donors; a = for some, but not all, variables; b = calculated from refusal rates; c = calculated from potential and actual donors; d = multiple organs remove
Half of the studies (n = 6; 50%) used an interrupted time series design, while 3 (25%) studies used cohort designs, and 3 (25%) used a before-and-after study design. The period of data collection in the studies ranged from 1 year (13, 14) to 11 years (15). Several different organ donation outcomes were reported in included studies: consent or refusal rate (n = 8; 67%) (14–21), number of potential organ donors (n = 7; 58%) (15, 17–20, 22, 23), number of actual organ donors (n = 7; 58%) (17–20, 22–25), number of deceased donor transplantations (n = 4; 33%) (19, 20, 22, 24), conversation rate (i.e., how many potential donors become actual donors) (n = 4; 33%) (18–20, 23), number of organs removed (n = 3; 33%) (20, 24, 25), and number of multiple organs removed (n = 2; 17%) (19, 25) (Table 1).
Methodological Quality of Included Studies
All studies were rated as “weak” in methodological quality. Reasons for reduced quality scores were largely around sampling and statistical analyses. The quality ratings for each included study is presented in the supplementary file (see Additional file 3 for studies with an interrupted time series study design; see Additional file 4 for cohort and before-and-after study design).
Organ Donation Outcomes
Potential Organ Donors. Of the studies reporting on potential organ donors (n = 7), four reported data as absolute values (18, 19, 22, 23), two as donors per million (15, 17), and one as percent change (20). All seven studies found a relative increase, between 8% (15) and 143% (20), in potential organ donors following implementation of donation physicians (median increase, 33%). Among the interrupted time-series studies (Figure 2A-B), the average relative year-to-year increase in potential organ donors across all studies ranged from 8% (15) to 67% (22). Among the before-and-after studies (Figure 2C), the relative percent change in potential organ donors ranged from 27% (19) to 143% (20).
Actual Organ Donors. Of the studies reporting on actual organ donors (n = 7), three reported data as part per million (17, 20, 24) and four as the absolute value (18, 19, 22, 23). All seven studies found an increase between 15% (25) and 113% (18) in actual organ donors following implementation of donation physicians (median increase, 27%). Among interrupted time series studies (Figure 3A-B), the average relative year-to-year increase in actual organ donors ranged from 15% (25) to 73% (23). Among the before-and-after studies (Figure 3C), the relative percent change in actual donors ranged from 24% (19) to 113% (18).
Donor Consent Rate. Of the studies reporting donor consent or refusal rates (n = 8), the average relative change in donor consent rates ranged from -3 to 258% (median increase, 12%). Among interrupted time series studies (Figure 4A-B), the average relative increase in the year-to-year percent change in donor consent rates ranged from 1% (15) to 17% (17). In before-and-after studies (Figure 4C), the average relative increase in donor consent rate ranged from -1% (19) to 11% (18). In cohort studies (Figure 4D), the relative percent change in donor consent rate varied from 5% (16) to 259% (14).
Organ Procurement.Of the three studies (20, 24, 25) reporting on single organs procured, two reported data as absolute numbers (24, 25) and one as per donor (20). The change in single organs procured (Additional file 5) ranged from 16% (20) to 81% (24, 25). Both studies (19, 25) reporting on the procurement of multiple organs provided data as a percent change (Additional file 6). For the interrupted time series study, the average relative year-to-year increase was 38% (25) and for the before-and-after study, the average relative change in multiple organs procured was 4% (19).
Transplants. Four studies (19, 20, 22, 24) reported on the number of transplants from deceased donors (Additional file 7). Of these, two reported data as absolute numbers (19, 22), two as per donor (19, 20), and one as part per million (24). Among all studies, there was an increase in deceased donor transplants from 13 to 24% (median increase, 19%). Among interrupted time series studies, the average relative year-to-year increase in deceased donor transplants ranged from 13% (24) to 24% (22). Among before-and-after studies, the average relative year-to-year increase in deceased donor transplants ranged from 13% (20) to 20% (19).
Organ Donor Conversion Rate. Of the four studies (18–20, 23) reporting on organ donor conversion rates (Additional file 8), three reported data as percent of potential donors (18, 19, 23) and one as percent of actual brain deaths (20). Among interrupted time series data, the average relative year-to-year increase in the organ donor conversion rate was 30% (23). Among before-and-after studies, the relative percent change in organ donor conversion rates ranged from 6% (18) to 23% (20) among studies reporting a positive change and a -3% percent change in one study reporting a decrease (19).