Table 1:

Overview of the studies

Author, date, country, study type (level of evidence)	Patient group	Outcomes	Key results	Comments/weaknesses
Kron et al., 1993, USA [2] Prospective study (level 3)	11 MDs; period: 1990–92	Hospital survival	Nine of the ten lung transplant did well Donor pool expanded by 36%	First report in the literature; small number of patients; follow-up not specified
Sundaresan et al., 1995, USA [3] Cohort study (level 3)	Study group: 44 MDs; Control group: 89 SDs; Period: 1991–94	Hospital outcomes (A-a gradient, MV duration, 30 days mortality)	No differences between the groups. CPB used more frequently to implant the second lung when MDs (20 vs 13%, P = ns)	Pioneer work; analysis restricted to MDs with PO2 < 300 mmHg; recipient severity of illness was not considered in the analysis
		Survival	Study group: 86.4%; control group: 83.2%; P = ns
Gabbay et al., 1999, Australia [4] Cohort study (level 3)	Study group: 64 MDs (subgroup of 20 with initial suboptimal gas exchange); Control group: 48 SDs; Period: 1995–98	Hospital outcomes (ICU stay, PaO2/FiO2 at T0 and T24 h, 30-day mortality)	No differences between groups. Graft ischaemic time predict the recipient PaO2/FiO2 ratio	High MD percentage (57%); large number of donors with two criteria of marginality
		Survival (1, 2 and 3 years)	No differences between groups
Bhorade et al., 2000, USA [5] Cohort studies (level 3)	Study group: 52 MDs; Control group: 62 SDs; Period: 1996–99	Short-term outcomes (OR and ICU complications)	No differences between groups	Exclusion of SLT or HLT; first report concerning follow-up at 1 year; difference in sex recipients (>female in the MD group, P < 0.05)
		Middle- and long-term outcomes (acute rejection episodes, 1-year pulmonary function and survival)	No differences between groups
Pierre et al., 2002, Canada [6] Cohort study (level 3)	Study group: 63 MDs; Control group: 60 SDs; Period: 1997–2000	Hospital outcomes (time on CPB, 30- and 90-day mortality, PaO2/FiO2 in ICU, ICU length of stay)	Higher 30-day mortality (17.5 vs 6.2%, P = 0.047) and 90-day mortality (22.2 vs 7.7%, P = 0.0391) in the MD group Higher mortality associated with bronchoscopy and chest X-ray alterations RR = 1.92 for SD and NG recipients vs MD and NG recipients	High MD percentage (51%); lack of intermediate and long-term outcomes; study not adjusted for differences in recipient severity of illness
Thabut et al., 2005, France [7] Multicenter retrospective study (level 3)	785 patients (n = 270 SLT; n = 251 BLT; n = 264 HLT)	Early graft function (best recipient PaO2/FiO2 ratio within the first 6 PO hours and MV duration); long-term survival	Donor gas exchange before harvest was significantly associated with recipient early gas exchange, duration of MV and survival Increase RR of death when donor PaO2/FiO2 before harvest <350 mmHg (RR = 1.43; P = 0.01) Donor and recipient sex mismatch significantly associated with survival	Smoking history of most lung donor was not recorded; duration of MV only available in three centres (380 patients)
Lardinois et al., 2005, Switzerland [8] Cohort study (level 3)	Study group: 63 MDs; Control group: 85 SDs; Period: 1992–2003	Hospital outcomes (MV duration, ICU stay, PO complications, 30-day mortality) Intermediate outcomes: spirometry at 6 months, 1-year mortality)	No differences between groups in hospital or intermediate outcomes No differences in survival when analysing the different periods or the number of MD criteria Low PO2 level and positive bronchoscopy associated with higher risk of 30-day and 1-year mortality	First report that analyses the impact of MDs with one or more than one criteria; more female and higher age in the MD group
Aigner et al., 2005, Austria [9], Cohort study (level 3)	Study group: 23 MDs; Control group: 60 SDs; Period: 2001–02	Hospital outcomes (surgical procedure and complications, 30-day mortality, ICU and hospital stay) 3 Months and actuarial survival BOS incidence Lung function test after transplantation	No differences between groups in hospital or intermediate outcomes	Small sample size in the study group; introduction of inhalative drug abuse as extended criteria
Kawut et al., 2005, USA [10] Cohort study (level 3)	Study group: 27 MDs; Control group: 24 SDs; Period: 2001–03	Primary endpoints: MV and ICU-free days, time to hospital discharge, spirometry at 1 year	Recipient of MDs had less ICU-free days (P = 0.002), longer time to hospital discharge (P = 0.007) and worsen pulmonary function (FEV1%, FEV1/FVC, FEF25–75, P < 0.05) at 1 year	Small sample size; eight deaths in the cohort limiting the power to detect a difference in survival
		Secondary endpoints: intra-operative complications, pneumonia, sepsis and survival	No difference in survival: 30-day survival = 96% in both group
Luckraz et al., 2005, UK [11] Cohort study (level 3)	Study group: 50 MDs with PO2 level <300 mmHg; Control group: 312 SDs with PO2 level >300 mmHg; Period: 1984–2001	Hospital outcomes (CPB and ischaemic time, MV duration, 30-day mortality) Infectious and rejection rate, risk of BOS 1- and 5-year survival	Recipient of MDs had higher 30-day mortality (22 vs 13%, P = 0.08) and a lower rejection rate after 3 months (P = 0.05) No differences in other outcomes between groups	Long period of analysis; higher age of the donor and lower age of the recipient in the MD group
Botha et al., 2006, UK [12] Cohort study (level 3)	Study group: 83 MDs; Control group: 118 SDs; Period: 2000–2004	Hospital outcomes (ischaemic time, 30- and 90-day mortality, PGD score, A-a gradient, MV duration, ICU stay) Intermediate outcomes (survival, incidence of BOS, BOS-free survival)	Recipient of MDs had a higher rate of grade 3 PGD (43.9 vs 27.4%, P = 0.015), higher mean A-a gradient at 24 h (148 vs 115 mmHg, P = 0.021), higher 90-day organ-specific mortality (15.7 vs 5.1%, P = 0.012) and on BLT higher 30- and 90-day mortality No differences in other outcomes (survival, incidence of BOS, BOS-free survival) between groups	Larger number of patients; MDs with more than 1 criteria were 30%; recipient of MDs had higher mean age
Meers et al., 2010, Belgium [13] Cohort study (level 3)	Study group: 27 MDs; Control group: 23 SDs; Period: 2006–07	Hospital outcomes (use of CPB, PGD, mortality, ICU and hospital stay) 1- and 2-year survival	Recipient of MDs had higher ICU stay (7 vs 4 days, P < 0.03) and the PGD rate at 24 h (P < 0.04) No differences in the other early and intermediate outcomes	Small number of patients; minority of MDs with low PO2 levels and more than 1 extended criteria
Berman et al., 2010, UK [14] Cohort study (level 3)	Study group: 184 MDs based on smoking status; Control group: 240 non-smoking donors; Period: 1995–2008	Hospital outcomes (ICU stay, MV duration) Intermediate and long-term outcomes (3 months and 1-year survival, 3 months and 1-year chronic rejection and infectious rates)	Recipient for smoking donors had higher ICU stay (>2 days, P = 0.004), lower 3 months survival (13 vs 21%, P = 0.04), 20% higher risk of MV > 10 days (P = ns) No difference in rejection or infection rates	Smoking donors are older than non-smoking donors
Pizanis et al., 2010, Germany [15] Cohort study (level 3)	Study group: 19 MDs based on age ≥55 years; Control group: 186 SDs (age <55 years); Period: 2000–08	Hospital outcomes (ischaemia time, time on CPB, initial oxygenation capacity, ICU and hospital stay, MV duration, mortality) Intermediate and long-term outcomes (spirometry at 6, 12, 36, 60 months; 1-, 3- and 5-year survival; the BOS occurrence rate after 5 years	No significant differences in early, intermediate and long-term outcomes Spirometric function: trend towards a lower percentage from 36 months PO in the MD group	Small number of patients in the MD group; all BLT performed with CPB

A-a, alveolar arterial; BLT, bilateral lung transplantation; BOS, bronchiolitis obliterans syndrome; CPB, cardiopulmonary bypass; FVC, forced vital capacity; FEV1, forced expiratory volume in 1 s; FEF25–75, mean forced expiratory flow during the middle half of forced vital capacity; HLT, heart–lung transplantation; ICU, intensive care unit; MD, marginal donor; MV, mechanical ventilation; NG, non-guideline; OR, operating room; PGD, primary graft dysfunction; PO, post-operative; RR, relative risk; SD, standard donor; SLT, single lung transplantation.