Table 4.

Studies evaluating patient selection issues

Surgery type	Study	JBI quality score	Country	Population	Outcome measure	Results
Cataract	Barbieri et al. 2007	0.88	Austria	Patients admitted to hospital who were diagnosed with cataracts or underwent cataract surgeries in Austria, from 2001–2002. Public hospitals in 2001 (48 443 patients) and of public (47 797 patients) and private hospitals (5100 patients) in 2002. Age: 73.77 ± 10.86 (public hospital), 75.01 ± 9.4 (private hospital)	complex patients	Public hospitals often did additional procedures during one staying period (8773 vs. 1337). The rates for cataract intervention in both eyes and for one single intervention were 7.01% (0.75; 13.29) and 92.98% (86.71; 99.25) in public hospitals. In private hospitals, these rates were 2.47% (0; 5.91) and 97.53% (94.09; 100).
	Browne et al. 2008	0.73	UK	769 patients (inguinal hernia, varicose vein, and cataract) treated in six private and 1895 treated in 20 public facilities in England during 2006–07. Age: 73.7 ± 10.6 (cataract public), 74.6 ± 10.0 (cataract private), 66.2 ± 14.6 (hip public), 66.8 ± 14.1 (hip private), 66.2 ± 16.5 (knee public), 66.7 ± 12.2(knee private).	complex patients	Patients undergoing day surgery in ISTCs were healthier and had a less severe primary condition than those in NHS facilities. Poor or fair health mean (SD): cataract, NHS: 131 (22.3), ISTC 45(16.4). Hip replacement, NHS: 62(21.5), ISTC 27(14.9). Knee replacement, NHS 68(21.7), ISTC 21(11.5).
	Kruse et al. 2019	0.82	Netherlands	50 000 patients who received cataract care (including academic and tertiary hospitals) from 2013 to 2015. Average age: 72.26 ± 9.77 (private) vs. 73 ± 10.1 (public)	complex patients	The mean age is lower in private clinics, 72.26(9.77) vs. 73.20(10.10). The percentage of patients who are 85 years or older is much lower in private clinics (8.32%) than in general hospitals (10.29%). The average number of chronic conditions shows that private patients have less comorbidity, 2.15(1.65) vs. 2.24(1.72).
	Pager and McCluskey 2004	0.80	Australia	Cataract surgery patients. Forty-two public patients and 39 private patients in Sydney, Australia between April and June 2002. Average age: 71.7 ± 9.6 (private) vs. 72.9 ± 9.4 (public)	complex patients	Preoperative VF-14 scores were 86.5 ± 11.7 for private patients and 79.0 ± 19 for public patients (p = 0.035).
	Solborg et al. 2015	0.73	Denmark	Cataract Surgery patients in Denmark between 2004 and 2012. 243 856 patients (411 140 cataract operations).	complex patients	The mean age at first eye cataract surgery in private hospitals/clinics was 0.61 years lower compared to the mean age at first eye cataract surgery in public hospitals (95% CI: 0.36–0.87, p < .001). Patients who had cataract surgery in private hospitals were healthier.
	Solborg et al. 2013	0.73	Denmark	Patients who received primary hip replacement funded by the English NHS for financial year 2006–2007. (42 948 patients, of which 1 841 were treated at 173 public treatment centers and 6 specialized treatment centers, and 938 by 14 private treatment centers).	postoperative infection treatment	All endophthalmitis cases after cataract surgery (36% performed at public hospitals and 64% performed at private hospitals) were treated in public hospitals.
Orthopedic	Bannister et al. 2010	0.73	UK	Hip and knee arthroplasty patients in the UK from October 2003 to March 2005. Patients who had 880 total hip and 874 total knee arthroplasties at a regional orthopedic hospital with 368 total hip and 365 total knee arthroplasties from an NHS and 67 total hip and 86 total knee arthroplasties from a private hospital independent treatment center.	patient rejection (complexity of the surgery or comorbidity)	Reasons for rejection at public hospitals were co-morbidity in 4.2% and complexity of surgery in 1%. At private hospitals, 23.2% were rejected on medical or surgical grounds.
	Chard et al. 2011	0.82	UK	Patients undergoing hip or knee replacement (5671 in ISTCs and 14 292 in NHS), inguinal hernia repair (640 and 2023, respectively), or surgery for varicose veins (248 and 1336, respectively) in the UK from June 2008 to September 2009.	complex patients	Patients in ISTCs were healthier than those in NHS providers, had less severe preoperative symptoms, and were more affluent, though the differences were small.
	Cooper et al. 2018	1	UK	All elective hip and knee replacements (478 226) on patients aged 55–100 performed between financial years 2002/3 and 2008/9 in England.	complex patients	ISTC entry led nearby public hospitals to experience an 11.6% increase in patients’ average illness severity as captured by the Charlson score – or a 6.2 percentage point increase in the proportion of patients with a Charlson score of three or more.
	Heath et al. (2022)	0.82	Australia	Patients undergoing primary THR (specifically total conventional hip replacement) or TKR for osteoarthritis between July 2018 and April 2020 who participated in the AOANJRR PROMs program (4330 THR patients and 7054 TKR patients). Mean age: 66.48 ± 11.28 (public hip replacement patients), 67.01 ± 11.28 (private hip replacement patients), 66.17 ± 9.08 (public knee replacement patients), 66.57 ± 8.43 (private knee replacement patients)	Preoperative symptom severity	The preoperative estimated mean Oxford Hip Score was significantly higher (reflecting less symptoms) for patients having surgery in private versus public hospitals (21.39 versus 18.11, [mean difference 3.27, 95% CI 1.81, 4.79]). For TKR, there was a significant interaction between BMI and hospital type and a significant interaction between gender and hospital type where the largest difference in Oxford Knee Score between private and public hospitals was seen among underweight/normal BMI patients (mean difference of 4.68, 95% CI 2.99, 6.37).
	Holom and Hagen 2017	0.91	Norway	All publicly financed patients having primary total hip (37 897 patients) or primary total knee arthroplasty (25 802 patients) at one of the three hospital types from 2009 to 2014 in Norway. Average age: 66.07 ± 10.18 (private) vs. 68.26 ± 11.20 (public)	complex patients	Patients who had surgery at private facilities had the lowest average Charlson Comorbidity Index. Mean, SD private (0.116, 0.4340 vs. public (0.263, 0.798).
	Kelly and Stoye 2020	0.82	UK	Elective hip replacement patients (615,281 patients) between April 2002 and March 2013.	comorbidity	The mean number of comorbidities was 1.83(0.6) for patients treated in private facilities and 3.10(1.86) for the ones treated in NHS hospitals.
	Moscone et al. 2019	0.73	Italy	Acute myocardial infarction, stroke, hip and knee replacement patients admitted to 189 Italian hospitals located in the Lombardy region between 2012 and 2014. Age: 68.25 (hip replacement), 70.12 (knee replacement)	complex patients	Severe patients with a higher Elixhauser comorbidities index who require hip and knee surgery were less likely to be admitted to private facilities. Hip replacement, Elixhauser comorbidities index 0.023(0.3866) private vs. public 0.116(0.386). Knee replacement, Elixhauser comorbidities index 0.030(0.204) private vs. 0.135(0.421) public.
Both	Street et al. 2010	0.73	UK	Patients receiving care for one of several defined healthcare resource groups (including hip and knee replacements) in the UK in financial year 2006/07. A total of 3 334 535 patients are included in the analysis, of which 77 358 (2.3%) were treated in treatment centers. Age: 69.72 ± 9.58 (knee patients), 70.66 ± 10.35 (hip patients)	complex patients	Patients treated in public centers were younger, more likely to have come from deprived areas, and tended to have more diagnostic and procedure codes than those treated in private centers.