Krogh 2013.

Methods	Randomised controlled trial: endpoint assessors and participants were blinded to the procedure. Allocation sequence controlled by randomisation performed as blocks of 6 participants. Study's outcomes were measured at 3 months Trial conducted: Diagnostic Centre, Region Hospital Silkeborg, Silkeborg, Denmark; recruitment: from January 2009‐July 2010
Participants	Participants: 40 with elbow lateral epicondylitis Included participants: participants with symptoms for more than 3 months Excluded participants: participants < 18 years old; treated with glucocorticoid injection in previous 3 months; previous tennis elbow surgery; inflammatory diseases; neck pain on the ipsilateral side and chronic pain syndromes Lateral epicondylitis defined as pain on the lateral side of the elbow for at least 3 months, pain at the lateral epicondyle on direct palpation and during resisted dorsiflexion of the wrist. Ultrasonography was also performed at the origin of the extensor tendon; required a definite sign of tendinopathy with colour Doppler flow of at least grade 2 at baseline Age: PRT group mean (SD): 47.6 years (7.1) No PRT mean (SD): 44.7 years (7.9) Gender: PRT group (number of men:women): 9:11 No PRT (number of men:women): 9:11 Sports activity: not available
Interventions	All participants underwent platelet‐rich plasma or glucocorticoid or saline ultrasound‐guided single injection. A blood sample was collected from all participants, and all interventions were prepared out of the reach of the participant PRT (number of participants = 20): PRP: 3.0‐3.5 mL PRP derived from 27 mL blood. Blood was centrifuged at 3200 rpm for 15 minutes, before the addition of 3 mL citrate. Bicarbonate was added to the PRP to achieve physiological pH. PRT preparation: Recover GPS II system (Biomet Biologics Inc, Warsaw, Indiana) Quantification of platelet concentrates after preparation: 8‐fold (compared with whole blood) No PRT (number of participants = 20): saline (3 mL of 0.9%) Co‐interventions: same rehabilitation protocol for both groups
Outcomes	Pain section of the PRTEE questionnaire Functional disability of the PRTEE questionnaire Safety (adverse events) Injection‐related pain Ultrasound assessment: colour doppler changes and tendon thickness
Other quality issues	Sample size: the authors calculated the sample size based on the PRTEE pain domain at 12 months (we expect that this based on another population) Validation of PRT: quantification reported
Notes	We excluded all the analyses relating to glucocorticoid intervention (not considered as placebo) The authors provided the study protocol/trial registration details, ID: NCT 01109446
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation	Low risk	Used permuted blocks of 6 participants
Allocation concealment	Low risk	Used sequentially‐numbered, opaque and sealed envelopes
Blinding All outcomes	Low risk	The participant and outcome assessors were blinded to the treatment, but the treating physician was not
Incomplete outcome data addressed All outcomes	High risk	Only 13 out of 40 participants in the 2 groups completed 12 months' follow‐up
Free of selective reporting	High risk	The study protocol is not available and the clinical follow‐up period was short for participants who underwent elbow tendinopathy treatment
Free of other bias	Low risk	The study appears to be free of other sources of bias