Validity, reliability, and responsiveness of the Self-reported Foot and Ankle Score (SEFAS) in forefoot, hindfoot, and ankle disorders

Figures & data

Table 1. Patient data

	Patients with forefoot disorders	Patients with midfoot/hindfoot/ankle disorders
No.	118	105
Age
Median (range)	57 (16–87)	55 (18–81)
Sex
Male (%)	22 (19%)	46 (44%)
Female (%)	96 (81%)	59 (56%)
Height, cm
Mean (SD)	169 (8.6)	172 (10.8)
Weight, kg
Mean (SD)	74 (13.4)	84 (15.6)
Diagnosis
Arthritis	4	33
Achilles tendon disorders	0	12
Flatfoot	0	26
Cavovarus/neurological	2	21
Great toe disorders	91	0
Lesser toe disorders	17	0
Others	4	13
Surgery
Arthrodesis	10	38
Calcaneal osteotomy	0	32
Tendon surgery	0	18
Osteotomy first metatarsal	77	1
Surgery in lesser toes	18	0
Tendon transfers	1	9
Others	11	7

Table 2. Validity, reliability, and measurement error of 4 different questionnaires evaluating patients with forefoot disorders. Correlation analyses compared SEFAS with the other questionnaires. Data are presented as mean with 95% confidence interval (CI), as standard deviation (SD), or as percentage (%). Agreement is presented as S_method with CV% witihin brackets

	Validity				Reliability			Agreement
Questionnnaires	Spearman Rho (CI)	Pearson (CI)	Floor and ceiling effects (%)	Test mean (SD)	Retest mean (SD)	ICC (CI)	Cronbach's α	Smethod
No.	118	118	118	37	37	37	118	37
SEFAS	_	_	0	29 (8)	30 (8)	0.92 (0.85–0.96)	0.84	2.3 (8%)
FAOS
Pain	0.82 (0.75–0.87)	0.83 (0.76–0.88)	3	66 (21)	70 (19)	0.91 (0.84–0.95)	0.91	6.6 (10%)
Symptoms	0.64 (0.52–0.74)	0.63 (0.51–0.73)	8	79 (15)	83 (15)	0.81 (0.67–0.90)	0.78	6.9 (9%)
ADL	0.75 (0.66–0.82)	0.75 (0.65–0.82)	8	78 (22)	81 (19)	0.92 (0.85–0.96)	0.97	6.1 (8%)
Sport/Recreation	0.52 (0.37–0.64)	0.52 (0.37–0.64)	12	53 (28)	48 (28)	0.81 (0.66–0.90)	0.89	12.4 (25%)
Quality of life	0.75 (0.66–0.82)	0.74 (0.65–0.81)	2	44 (20)	46 (21)	0.79 (0.62–0.88)	0.81	9.4 (21%)
EQ-5D	0.57 (0.43–0.68)	0.60 (0.47–0.71)	15	0.7 (0.3)	0.7 (0.2)	0.72 (0.51–0.85)	0.52	0.1 (19%)
Visual analog scale (VAS)	0.41 (0.25–0.55)	0.46 (0.30–0.59)	4	72 (20)	73 (16)	0.92 (0.85–0.96)	–	4.6 (6%)
SF-36
Physical functioning (PF)	0.69 (0.58–0.78)	0.72 (0.62–0.80)	4	66 (23)	66 (20)	0.85 (0.73–0.92)	0.88	8.1 (12%)
Role limitations,
physical (RP)	0.43 (0.27–0.57)	0.44 (0.28–0.57)	58	64 (41)	64 (42)	0.82 (0.67–0.90)	0.86	16.6 (26%)
Bodily pain (BP)	0.71 (0.61–0.79)	0.73 (0.63–0.80)	3	46 (18)	49 (18)	0.82 (0.68–0.91)	0.84	7.9 (17%)
General health (GH)	0.27 (0.09–0.43)	0.31 (0.13–0.46)	7	77 (17)	78 (19)	0.74 (0.53–0.86)	0.81	8.9 (11%)
Vitality (VT)	0.48 (0.33–0.61)	0.52 (0.37–0.64)	2	62 (23)	69 (19)	0.86 (0.73–0.93)	0.82	9.1 (14%)
Social functioning (SF)	0.40 (0.24–0.54)	0.39 (0.22–0.53)	50	88 (19)	88 (19)	0.76 (0.58–0.87)	0.80	9.3 (11%)
Role limitation,
emotional (RE)	0.19 (0.01–0.36)	0.18 (–0.01–0.35)	74	90 (24)	87 (30)	0.66 ( 0.42–0.81)	0.78	13.0 (15%)
Mental health (MH)	0.26 (0.08–0.42)	0.25 (0.07–0.41)	7	80 (18)	82 (17)	0.90 (0.82–0.95)	0.82	5.8 (7%)

Table 3. Validity, reliability, and measurement error of 4 different questionnaires evaluating patients with hindfoot or ankle disorders. Correlation analyses compared SEFAS and the other questionnaires. The time it took to complete the questionnaires is presented for the different questionnaires. Data are presented as mean with 95% confidence interval (CI), as standard deviation (SD), or as percentage (%). Agreement is presented as S_method with CV% witihin brackets

	Time(s)	Validity				Reliability			Agreement
Questionnnaires		Spearman Rho (CI)	Pearson (CI)	Floor and ceiling effects (%)	Test mean (SD)	Retest mean (SD)	ICC (CI)	Cronbach's α	Smethod
No.	19	106	106	106	52	52	52	106	52
SEFAS	158	–	–	0	19 (9)	20 (9)	0.93 (0.88–0.96)	0.86	2.4 (13%)
FAOS	394
Pain		0.82 (0.75–0.87)	0.83 (0.76–0.88)	2	51 (25)	49 (25)	0.92 (0.87–0.96)	0.93	7.0 (14%)
Symptoms		0.65 (0.52–0.75)	0.70 (0.58–0.78)	1	51 (25)	50 (26)	0.92 (0.87–0.95)	0.80	7.1 (14%)
ADL		0.68 (0.56–0.77)	0.71 (0.59–0.79)	4	59 (23)	57 (23)	0.92 (0.86–0.95)	0.97	6.8 (12%)
Sport/Recreation		0.62 (0.49–0.73)	0.62 (0.48–0.72)	34	18 (20)	20 (24)	0.67 (0.72–0.90)	0.85	12.7 (67%)
Quality of life		0.67 (0.55–0.76)	0.67 (0.54–0.76)	15	22 (15)	25 (17)	0.83 (0.72–0.90)	0.74	6.6 (28%)
EQ-5D	95 ^a	0.59 (0.45–0.70)	0.53 (0.37–0.66)	7	0.5 (0.3)	0.5 (0.3)	0.62 (0.41–0.76)	0.53	0.2( 35%)
Visual analog scale (VAS)		0.51 (0.35–0.64)	0.52 (0.36–0.65)	3	63 (20)	62 (21)	0.91 (0.85–0.95)	–	6.1 (10%)
SF-36
Physical functioning (PF)	388	0.65 (0.52–0.75)	0.64 (0.51–0.74)	4	41 (24)	40 (23)	0.89 (0.82–0.94)	0.90	7.8 (19%)
Role limitations, physical (RP)		0.36 (0.18–0.52)	0.42 (0.25–0.57)	70	24 (36)	18 (31)	0.52 (0.28–0.69)	0.86	13.8 (61%)
Bodily pain (BP)		0.71 (0.60–0.79)	0.73 (0.63–0.81)	6	42 (24)	41 (27)	0.88 (0.81–0.93)	0.78	8.5 (20%)
General health (GH)		0.37 (0.19–0.53)	0.35 (0.17–0.51)	4	64 (24)	64 (22)	0.89 (0.81–0.93)	0.81	7.7 (12%)
Vitality (VT)		0.51 (0.35–0.64)	0.52 (0.37–0.65)	3	51 (25)	46 (26)	0.88 (0.79–0.93)	0.83	9.6 (20%)
Social functioning (SF)		0.50 (0.34–0.63)	0.51 (0.35–0.64)	32	69 (28)	68 (26)	0.88 (0.80–0.93)	0.86	9.3 (14%)
Role limitation, emotional (RE)	0.37 (0.19–0.53)	0.37 (0.19–0.53)	71	59 (44)	58 (45)	0.79 (0.65–0.88)	0.86	18.1 (31%)
Mental health (MH)		0.43 (0.26–0.58)	0.40 (0.23–0.55)	5	71 (20)	72 (20)	0.89 (0.81–0.94)	0.85	6.6 (9%)

^a The time for completing EQ-5D questionnaire together with EQ VAS.

Agreement in scores of patients with forefoot disorders (n = 37) and of patients with hindfoot or ankle disorders (n = 52) for SEFAS presented as Bland-Altman plots (Bland and Altman 1986). The solid line represents the mean value and the dotted lines show the limits for 2 standard deviations (SDs) above and below the mean value.

Table 4. Pre- and postoperative values in 68 patients operated due to forefoot disorders, with responsiveness expressed as effect size (ES) and standardized response mean (SRM). Data are presented as mean with 95% confidence interval. Due to missing answers in some questionnaires, the numbers of fully filled questionnaires are presented in parentheses in the left-hand column (n)

Questionnaire	Preoperatively, mean	Postoperatively, mean	ES (95% CI)	SRM (95% CI)
SEFAS (n = 66)	29	38	1.29 (0.95–1.63)	1.27 (0.93–1.61)
FAOS (n = 68)
Pain	66	87	1.10 (0.78–1.42)	1.10 (0.82–1.46)
Symptoms	78	84	0.38 (0.12–0.64)	0.39 (0.13–0.65)
ADL	77	92	0.76 (0.50–1.02)	0.92 (0.65–1.19)
Sport/Recreation	47	70	0.82 (0.54–1.10)	0.77 (0.49–1.05)
Quality of life	44	75	1.48 (1.12–1.84)	1.32 (0.98–1.66)
EQ-5D (n = 64)	0.68	0.87	0.95 (0.60–1.30)	0.90 (0.56–1.24)
VAS (n = 64)	74	81	0.46 (0.21–0.71)	0.48 (0.23–0.73)
SF-36 (n = 66)
Physical functioning (PF)	65	85	0.94 (0.63–1.25)	0.75 (0.46–1.04)
Role limitations, physical (RP)	58	77	0.44 (0.16–0.72)	0.42 (0.14–0.70)
Bodily pain (BP)	48	77	1.57 (1.17–1.97)	1.15 (0.79–1.51)
General health (GH)	75	77	0.07 (–0.13 to 0.27)	0.09 (–0.11 to 0.29)
Vitality (VT)	65	74	0.45 (0.19–0.71)	0.43 (0.17–0.69)
Social functioning (SF)	84	91	0.37 (0.14–0.60)	0.43 ( 0.19–0.67)
Role limitation, emotional (RE)	84	92	0.27 (–0.01 to 0.55)	0.27 (–0.01 to 0.55)
Mental health (MH)	81	84	0.15 (–0.09 to 0.39)	0.14 (–0.10 to 0.38)

Table 5. Pre- and postoperative values in 68 patients operated on due to hindfoot or ankle disorders, with responsiveness expressed as effect size (ES) and standardized response mean (SRM). Data are presented as mean with 95% confidence interval. Due to missing answers in some questionnaires, the numbers of fully filled questionnaires are presented in the left-hand column (n)

Questionnaire	Preoperatively, mean	Postoperatively, mean	ES (95% CI)	SRM (95% CI)
SEFAS (n = 70)	20	29	1.05 (0.77–1.33)	0.99 (0.71–1.27)
FAOS (n = 74)
Pain	52	72	0.90 (0.66–1.14)	1.09 (0.83–1.35)
Symptoms	53	64	0.48 (0.27–0.69)	0.57 (0.35–0.79)
ADL	60	77	0.85 (0.62–1.08)	1.04 (0.79–1.29)
Sport/Recreation	20	35	0.70 (0.44–0.96)	0.57 (0.32–0.82)
Quality of life	22	46	1.57 (1.24–1.90)	1.18 (0.89–1.47)
EQ-5D (n = 72)	0.54	0.69	0.57 (0.28–0.86)	0.50 (0.21–0.79)
VAS (n = 67)	65	72	0.34 (0.06–0.62)	0.30 (0.02–0.58)
SF-36 (n = 73)
Physical functioning (PF)	40	56	0.73 (0.51–0.95)	0.83 (0.60–1.06)
Role limitations, physical (RP)	26	45	0.51 (0.24–0.78)	0.42 (0.16–0.68)
Bodily pain (BP)	41	57	0.73 (0.47–0.99)	0.62 (0.37–0.87)
General health (GH)	68	68	0.02 (–0.15 to 0.19)	0.03 (–0.14 to 0.20)
Vitality (VT)	54	62	0.35 (0.15–0.55)	0.45 (0.25–0.65)
Social functioning (SF)	71	78	0.24 (0.02–0.46)	0.27 (0.05–0.49)
Role limitation, emotional (RE)	57	68	0.24 (0.02–0.46)	0.25 (0.03–0.47)
Mental health (MH)	74	78	0.20 (0.00–0.40)	0.24 (0.04–0.44)