Joost Peerbooms

88 Chapter 6 for repeated measures were used. Multiple post hoc comparisons were corrected with the Bonferroni method. To determine whether the corticosteroid group and PRP group scored significantly different at a specific time point, Student t tests were used. The VAS pain score and DASH total scores were analysed according to the intention-to-treat principle (based on the allocated intervention) and according to the as-treated principle (based on the received treatment). Missing values are replaced by the last observed value of that variable for each individual (last observation carried forward). All statistical analyses were performed using the Statistical Package for the Social Sciences (version 17.0, SPSS, Chicago, Illinois). RESULTS FromMay 2006 to January 2008, a total of 100 eligible patients with epicondylitis were randomized into either a PRP injection group or a corticosteroid injection group. Six patients were lost to follow-up because of wrongful inclusion (Figure 1). Analysis of the baseline characteristics (age, sex, side, hand dominance, VAS score, DASH score) between the protocol-compliant patients and those lost to follow-up showed no significant differences ( P > .05). Sociodemographic and clinical characteristics of the participants are shown in Table 1. The PRP group and the corticosteroid group did not differ on demographic or clinical characteristics ( P > .05). However, at baseline, the PRP group did score significantly higher on the DASH total score compared with the corticosteroid group ( P < .0001). Table 1 Baseline Characteristics of the Corticosteroid and Platelet-Rich Plasma Groups α Corticosteroid Platelet-Rich Plasma P value (n = 49) (n = 51) Age, mean ± SD 47.3 ± 7.8 46.8 ± 8.5 .780 Male sex, no. (%) 23 (44.2) 23 (47.9) .712 Right side, no. (%) 32 (61.5) 30 (62.5) .921 Dominant hand 37 (75.5) 38 (74.5) .908 involved, no. (%) VAS, mean ± SD 67.1 ± 13.5 70.2 ± 15.2 .285 DASH, mean ± SD 44.1 ± 16.2 56.3 ± 17.7 <.0001 α SD, standard deviation; VAS, visual analogue scale; DASH, Disabilities of the Arm, Shoulder and Hand outcome measure