Table 3

Study characteristics and type of intervention

	Main author	Study date	Country	Subjects	Reference	Condition/specialty	Methods	Intervention type	SIGN quality score13	Outcomes measured	Findings
Descriptive designs
1	Fertig	1993	UK local	400 referrals (100 referrals per specialty)+a further 22 referrals by 21 PCPs	12	Orthopaedics ENT, gynaecology, ophthalmology	Descriptive case series	Referral guideline	3	Guideline compliance Referral rates	Most of referrals appropriate in comparison to guideline standards Guidelines unlikely to reduce referral rates
2	Kumar	1996–1997	UK local	100 referrals by ∼100 PCPs	26	ENT, tonsillectomy	Descriptive case series	Referral guideline for direct listing for surgery	3	Guideline compliance	Variable compliance by GPs with guidelines
3	Collins	1995	US national	Simulated case histories/vignettes;444 PCPs	27	Urology, benign prostatic hypertrophy	Cross-sectional survey	Referral guideline	3	Guideline compliance	Diagnostic evaluations vary from guideline standards
4	Fried-Lieb	1990–1991	US local	1796 preauthorisation requests to HRM	28	Orthopaedics, low back pain	Descriptive case series	Management guideline plus telephone based prior authorisation scheme	3	Appropriateness Cost	Use of conservative management increased Net savings
5	Rossi-Gnol	1988–1990	Canada international	456 referrals for 2147 randomly selected patients Quebec Workers Compensation Board	29	Orthopaedics, low back pain	Descriptive case series	Management guideline+referral guideline	3	Guideline compliance Referral rates Waiting times	Compliance with guideline, referral rates low and waiting times high in comparison to guideline standards.
6	Bishop	2003	Canada local	49 referrals	30	Orthopaedics, low back pain	Descriptive case series	Management guideline+referral guideline	3	Guideline compliance	Compliance variable—eg, good in examination; less good in imaging recommendations
7	Cerdan	2002–2004	Spain local	188 referrals made by 71 PCPs	31	General surgery	Descriptive case series	Guideline plus one-stop service	3	Guideline compliance Waiting times	Improved compliance Reduced waiting times
8	Arroyo	2000	Spain local	86 referrals by 26 PCPs	32	General surgery	Descriptive case series	Guideline plus one-stop service	3	Guideline compliance Waiting time	Guideline compliance high Waiting time reduced
9	Padilla	1995–1996	Spain local	400 referrals from five health centres	33	Urology, benign prostatic hypertrophy	Descriptive case series	Guideline plus one-stop service	3	Guideline compliance Waiting times	Compliance good Reduced waiting times
10	Norg	2005	Netherlands local	512 patients from 14 general practices	34	LUTS	Modelling study	Decision checklist	4	Compliance	Compliance estimated as high
11	Rao	2001–2002	UK local	8993 patients	35	Orthopaedics, musculoskeletal problems	Descriptive case series	Referral guidelines pro forma	3	Guideline compliance	High proportion of referrals compliant with guideline.
12	Lash	2005	UK local	62 referrals for cataract	36	Ophthalmology	Descriptive case series	National guidance	3	Guideline compliance	Compliance with “gold standard”
13	Fullen	2006	Ireland	54 referred patients	37	Orthopaedics, acute low back pain	Descriptive case series	Referral guideline	3	Guideline compliance	Referral practice not consistent with European guidelines

Controlled designs
1	Bradshaw	1997	UK local	147 referrals	25	General surgery	Mixed design	Referral guideline for direct listing for surgery	2−	Waiting times	Reduction in waiting time
2	Thomas	2003	UK local	959 referrals from 55 practices/health centres	15	Urology, LUTS; microscopic haematuria	Cluster RCT Allocation concealment+	Guideline plus “one-stop service”	1+	Guideline compliance Health outcomes Short Form Health Survey (SF-36) Waiting times Costs	Appropriate investigations increased in intervention group (0.5 (0.2–0.8) p<0.01) Reduced waiting times No change in patient outcome Reduction in hospital costs (£0.28–£43.00)
3	Emslie	1993	UK local	100 couples from 82 practices/health centres	19	Gynaecology, infertility	RCT Allocation concealment—not stated	Guideline plus structured management sheet	1−	Guideline compliance	Compliance with guideline increased for all targeted activities—eg, use of day 21 progesterone increased (72% intervention vs 41% control (p<0.001)
4	Morrison	1996/1997	UK local	689 referrals from 214 practices/health centres	16	Gynaecology Infertility	Cluster RCT Allocation concealment—not stated	Guideline plus structured management sheet	1−	Referral rates Guideline compliance Cost	No difference in referral rates. Appropriate investigations more likely to be carried out (OR 1.32(1.00–1.75) Non sig increase in costs.
5	Maddison	2001/2003	UK local	∼5000 referrals from ∼100 PCPs	20	Orthopaedics	Cohort study—historical controls	Guideline plus referral triage	2−	Referral rates Appropriateness Waiting time	Rates of referral increased (by 86%) Waiting times reduced Appropriateness (surgical conversion rate 37%) unchanged
6	Benninger	1994/1995	US local	163 referrals from 74 PCPs	21	ENT	Cohort study—historical controls	Management guideline+referral guideline	2−	Appropriateness of referral Waiting times	Appropriateness (45% (before), 70% (after; at 5 months), p<0.05) No change in waiting times
7	Rao	1994/1995	US national	550 referrals by PCPs referring to one secondary care centre	22	Orthopaedics, low back pain	Cohort study—historical controls	Management guideline+referral guideline	2−	Guideline compliance	No change in appropriateness of investigations
8	Goldberg	2001	US national	(No data on absolute numbers of referrals or referrers-only rates supplied)	17	Orthopaedics, low back pain	Cluster RCT (with time series analysis) No allocation concealment	Management guideline+referral guideline	1−	Surgery rates	Reduction of 8.9% surgical operations (20.9 per 100 000 population) over 30 months in intervention communities
9	Spata-fora	2000/2002	Italy national	1203 referrals (2465 patients) 450 PCPs	23	Urology, LUTS	Cohort study—historical controls	Management guideline+referral guideline	2−	Referral rates Guideline compliance Cost	Referral rates unchanged Compliance (eg, reduced use and cost of inappropriate investigation (33%–22%)) (p<0.001) Reduced costs=savings of 13.8%
10	Fender	1999	UK	1001 consultations (130 referrals)	18	Gynaecology, menorrhagia	Cluster RCT Allocation concealment+	“Educational package” based on principles of academic detailing	1+	Guideline compliance (with treatment recommendations) Referral rates	Recommended medication increased (OR 2.38 (1.61–3.49)) in intervention group and referral rate reduced (OR 0.64 (0.41–0.99))
11	Julian	2007	UK local	193 referrals from 157 general practices (99 intervention: 94 control)	24	Gynaecology, menorrhagia	Cohort study—concurrent controls	Management guideline+referral guideline	2+	Patient outcomes (surgery rates)	No difference in SF-36 scores Increased satisfaction in intervention group No difference in surgical rates

HRM, health risk management; LUTS, lower urinary tract symptoms; PCP, primary care practitioner; SIGN, Scottish Intercollegiate Guidelines Network.