Table 2

Intention-to-treat-analysis: results of the multivariable linear mixed model analysis with repeated measures and study group comparisons

No of weeks after start of interventionCustom-made insoleSham insoleUsual careCustom-made insole versus sham insole*Custom-made insole versus usual care†
MD (95% CI; P)RR (95% CI; P)Effect size/NNT (95% CI)MD (95% CI; P)RR (95% CI; P)Effect size/NNT (95% CI)
Pain at rest (crude mean (SD) score on pain numerical rating scale (0–10); lower score indicates less pain; adjusted mean difference measured between groups‡; effect size Hedges g)
63.99 (2.71)4.32 (2.53)3.48 (2.86)−0.41 (−1.11 to 0.29; 0.25)−0.15 (−0.48 to 0.19)−0.30 (−1.13 to 0.52; 0.47)−0.12 (−0.49 to 0.25)
123.29 (2.84)3.38 (2.72)3.21 (3.10)−0.34 (−1.03 to 0.35; 0.34)−0.14 (−0.48 to 0.19)−0.16 (−0.95 to 0.64; 0.70)−0.06 (−0.44 to 0.31)
262.39 (2.67)2.49 (2.71)2.55 (3.27)−0.33 (−1.00 to 0.34; 0.33)−0.17 (−0.50 to 0.16)−0.19 (−0.98 to 0.60; 0.64)−0.08 (−0.45 to 0.30)
Pain during activity (crude mean (SD) score on pain numerical rating scale (0–10); lower score indicates less pain; adjusted mean difference measured between groups§; effect size Hedges g)
65.72 (2.62)5.75 (2.21)4.43 (2.87)−0.07 (−0.61 to 0.47; 0.80)−0.04 (−0.37 to 0.30) 0.96 (0.25 to 1.68; 0.01)0.46 (0.08 to 0.84)
124.59 (3.00)4.69 (2.61)4.13 (2.61)−0.05 (−0.58 to 0.49; 0.87)−0.02 (−0.36 to 0.31) 0.94 (0.23 to 1.65; 0.01)0.45 (0.08 to 0.83)
263.98 (2.93)3.53 (3.00)3.42 (3.55)0.07 (−0.46 to 0.60; 0.80)0.04 (−0.29 to 0.37) 0.91 (0.20 to 1.62; 0.01)0.44 (0.07 to 0.82)
First step pain (crude mean (SD) score on pain numerical rating scale (0–10); lower score indicates less pain; adjusted mean difference measured between groups¶; effect size Hedges g)
65.82 (3.03)6.19 (2.41)4.55 (3.30)0.00 (−0.63 to 0.63; 1.00)0.00 (−0.33 to 0.33) 1.57 (0.73 to 2.40; 0.00)0.63 (0.25 to 1.02)
124.61 (3.45)4.84 (2.94)4.26 (3.58)0.01 (−0.61 to 0.63; 0.98)0.00 (−0.33 to 0.34) 1.48 (0.65 to 2.31; 0.00)0.60 (0.22 to 0.98)
263.77 (3.51)3.46 (3.20)3.11 (3.30)0.12 (−0.50 to 0.74; 0.71)0.06 (−0.28 to 0.39) 1.43 (0.61 to 2.26; 0.01)0.59 (0.21 to 0.97)
FFI-pain subscale (crude mean (SD) score on pain numerical rating scale (0–100); lower score indicates less pain; adjusted mean difference measured between groups**; effect size Hedges g)
648.21 (22.57)48.32 (20.29)37.23 (25.67)−1.35 (−5.60 to 2.91; 0.53)−0.09 (−0.43 to 0.24) 6.45 (1.10 to 11.80; 0.02)0.41 (0.04 to 0.79)
1237.70 (23.82)38.04 (22.47)36.17 (27.52)−1.07 (−5.38 to 3.24; 0.62)−0.07 (−0.41 to 0.26) 6.27 (0.84 to 11.69; 0.02)0.40 (0.03 to 0.78)
2631.68 (22.28)31.09 (27.43)26.26 (28.55)−0.87 (−5.41 to 3.68; 0.71)−0.06 (−0.39 to 0.27) 6.50 (0.84 to 12.15; 0.03)0.40 (0.03 to 0.78)
FFI-function subscale (crude mean (SD) score on function numerical rating scale (0–100); lower score indicates better function/less disability; adjusted mean difference measured between groups††; effect size Hedges g)
633.30 (25.24)32.77 (21.91)26.28 (23.23)1.12 (−4.40 to 6.34; 0.69)0.06 (−0.27 to 0.39) 7.46 (1.14 to 13.79; 0.02)0.38 (0.01 to 0.76)
1224.73 (23.87)23.33 (21.45)24.82 (22.98)1.77 (−3.69 to 7.22; 0.52)0.09 (−0.24 to 0.43) 7.37 (1.27 to 13.46; 0.02)0.39 (0.02 to 0.77)
2618.87 (22.47)18.87 (23.40)18.55 (25.53)1.89 (−3.54 to 7.32; 0.49)0.10 (−0.23 to 0.43) 7.07 (1.01 to 13.13; 0.02)0.38 (0.00 to 0.75)
FFI total (crude mean (SD) score on function numerical rating scale (0–100); lower score indicates better function/less disability; adjusted mean difference measured between groups‡‡; effect size Hedges g)
640.25 (22.61)40.09 (20.01)31.40 (23.99)−2.70 (−6.30 to 0.90; 0.14)−0.24 (−0.57 to 0.09)3.47 (−1.35 to 8.29; 0.16)0.26 (−0.11 to 0.64)
1230.83 (23.16)30.29 (20.98)30.16 (24.58)−2.30 (−6.18 to 1.57; 0.24)−0.19 (−0.53 to 0.14)3.26 (−1.85 to 8.37; 0.21)0.24 (−0.14 to 0.61)
2624.96 (23.08)24.61 (24.09)22.23 (24.51)−2.12 (−6.24 to 2.00; 0.31)−0.17 (0.50 to 0.17)3.31 (−2.08 to 8.69; 0.23)0.23 (−0.15 to 0.60)
Self-reported recovery (No (%) of participants reporting recovery of their plantar heel pain symptoms (Recovery=when participants have reported ‘completely recovered’ or ‘mostly recovered’ on a 7-point Likert scale); lower score indicates less recovery; adjusted RR measured between groups; NNT)
68/68 (11.4)7/69 (10.1)11/42 (26.2)2.01 (0.77 to 5.28; 0.16)61.7 (8.3 to −11.3) 0.34 (0.14 to 0.86; 0.02)−6.9 (−3.4 to 108.9)
1224/66 (36.4)25/69 (36.2)15/41 (36.6)1.22 (0.68 to 2.19; 0.50)759.0 (6.1 to −6.2) 0.48 (0.24 to 0.96; 0.04)−451.0 (−5.3 to 5.4)
2635/67 (52.2)39/68 (57.4)21/38 (55.3)1.01 (0.65 to 1.57; 0.96)−19.6 (−4.6 to 8.6)0.61 (0.34 to 1.08; 0.09)−33.1 (−4.4 to 6.0)
SF-12 physical health component (crude mean (SD) score on quality of life (0–100); lower score indicates less quality of life; adjusted mean difference measured between groups§§)
1242.19 (10.60)40.68 (9.18)41.41 (10.59)2.13 (−0.28 to 4.55; 0.08)1.00 (−1.67 to 3.68; 0.46)
2643.54 (10.82)43.50 (10.64)46.02 (10.47)1.62 (−0.79 to 4.03; 0.19)−0.27 (−2.89 to 2.34; 0.84)
SF-12 mental health component (crude mean (SD) score on quality of life (0–100); lower score indicates less quality of life; adjusted mean difference measured between groups¶¶)
1247.27 (10.21)50.04 (9.00)48.25 (8.90)3.70 (−6.49 to 0.92; 0.01)3.23 (−6.33 to −0.14; 0.04)
2647.54 (10.47)49.30 (9.19)48.97 (8.90)3.00 (−5.71 to 0.29; 0.03)−2.99 (−5.96 to −0.03; 0.05)
  • All analyses are adjusted for age, BMI, sex and activity level according to SQUASH.

  • *Sham group is reference group

  • †Usual care group is reference group;

  • ‡Analysis is also adjusted for educational level, bilateralism of pain, other musculoskeletal pain, self-reported illness in last 12 months, physical component of the SF 12 at baseline, mental component of the SF12 at baseline, pain score during activity and the disability subscore of the FFI at baseline.

  • §Analysis is also adjusted for duration of complaints, bilateralism of pain, the physical component of the SF12 at baseline, self-reported illness in last 12 months, other musculoskeletal pain, pain score at rest at baseline and the disability subscore of the FFI at baseline.

  • ¶Analysis is also adjusted for duration of complaints, bilateralism of pain, educational level, physical component of the SF12 at baseline, pain score at rest at baseline and the disability subscore of the FFI at baseline.

  • **Analysis is also adjusted for duration of complaints, bilateralism of pain, educational level, physical component of the SF12 at baseline, mental component of the SF12 at baseline, pain score at rest at baseline, pain score during activity at baseline, self-reported illness in last 12 months, other musculoskeletal complaints and the disability subscore of the FFI at baseline.

  • ††Analysis is also adjusted for duration of complaints, bilateralism of pain, educational level, physical component of SF12 at baseline, mental component of SF12 at baseline, pain score at rest at baseline, pain score during activity at baseline, self-reported illness in last 12 months and other musculoskeletal pain.

  • ‡‡Analysis is also adjusted for duration of complaints, bilateralism of pain, educational level, physical component of SF12 at baseline, mental component of SF12 at baseline, pain score at rest at baseline, pain score during activity at baseline, self-reported illness in last 12 months, other musculoskeletal pain and the disability subscore of the FFI at baseline.

  • §§Analysis is also adjusted for educational level, bilateralism of pain, pain score at rest at baseline, pain score during activity at baseline, self-reported illness in last 12 months and the disability subscore of the FFI at baseline.

  • ¶¶Analysis is also adjusted for duration of pain, bilateralism of pain, the physical component of the SF12 at baseline, pain score during activity at baseline, self-reported illness in last 12 months and other musculoskeletal pain.

  • BMI, body mass index; FFI, Foot Function Index; MD, mean difference; NNT, number needed to treat; RR, relative risk; SF12, The 12-Item Short Form Health Survey; SQUASH, Short Questionnaire to Assess Health-enhancing Physical Activity.