Effectiveness of custom-made foot orthoses in patients with rheumatoid arthritis: a randomized controlled trial

Depósito de investigación de la Universidad de Sevilla https://idus.us.es/ “This is an Accepted Manuscript of an article published by Sage in [Clinical rehabilitation] on [2019], available at: https://doi.org/10.1177/0269215518819118.” INTRODUCTION Foot involvement is an important problem for people with rheumatoid arthritis. The progression of the foot related symptoms is related to the duration and severity of the disease (1,2). The most frequent problems in the foot are pain increased plantar pressure, and decreased functional capacity which have a negative impact on quality of life and increase the risk of falling (1,3–5). The forefoot is commonly affected, especially the metatarsophalangeal joints (1). Common structural problems include hallux valgus deformity, deformities of the lesser toes, subluxation of the metatarsophalangeal joints, and displacement of the plantar fat-pad (3). One of the most prevalent foot deformities in rheumatoid arthritis patients is rearfoot valgus, which is associated with the presence of other deformities (6). The prescription of different types of foot orthoses is a common practice for patients with rheumatoid arthritis and foot pain symptoms. This treatment provides greater stabilization of the foot and ankle, which can reduce the risk of developing deformities, alleviate pain and the inflammation, and improve the functioning of the foot (3,5). Furthermore, they have been proven to be a cost-effective intervention (7). Foot orthoses have been used worldwide, but that of present the trial evidence is insufficient to know whether or not they are helpful. Thus, further research in this area is essential. This study aims at determining the effect of custom-made foot orthoses versus placebo flat cushioning insoles on pain, foot functionality, and quality of life in patients with rheumatoid arthritis. METHODS Study design and clinical setting A randomized controlled clinical trial was carried out according to the CONSORT guidelines (8). The study was registered in the Australian New Zealand Clinical Trials Registry (Trial ID: ACTRN12616000168459). The study was also approved by the Bioethics Committee of the Government of Andalusia (ID: 20161012141038) and authorized by the Head Office of the Clinical Area of Podiatry of the University of Seville (ID: INV22/15). The participating patients were recruited from the rheumatology unit of the following hospitals: Virgen de Valme, Virgen del Rocio, and Virgen de Macarena in Seville, as well as Hospital Basico de la Defensa in Ferrol (Galicia, Northern Spain). Participants were also recruited from the following patient associations: LIRA (Andalusian Rheumatologic League), AJEREA (Provincial Spondilitis and Arthritis Association), and ASEPAR (Sevillian Association of Patients with Rheumatoid Arthritis). All the participants gave written consent to be included in the study. The data were gathered in the Clinical Area of Podiatry of the University of Seville and in the Podiatric Clinic of the University of La Coruña. The start date and end date of the study were January 2016 and February 2018, respectively. The University of Seville was responsible for the integrity and conduct of the study. This study was non-funded with the exception of the cost of orthoses materials provided by the universities of Seville and La Coruña. These institutions had no influence in the results. Inclusion criteria and random allocation The inclusion criteria were age over 18 years, a diagnosis of rheumatoid arthritis according to the criteria of the American Rheumatism Association and the European League Against Rheumatism of 2010 (9), foot involvement, and no foot orthoses treatment for 30 days prior to the study. Patients were excluded if they had rheumatoid arthritis with acute symptomatic flare, ulcers, skin involvement, neurological problems, cognitive deterioration, or a need for walking assistance. Patients were excluded if they refused to change their footwear to use the foot orthoses. The participants were randomly assigned to one of the study groups. Group A was the experimental group and were given the custom-made foot orthoses, while group B was the control group and received a placebo treatment. Randomization was conducted by flipping a coin after making the foot orthoses and the placebo insoles. The allocation rule was stated in advance, that is, if the side showing a head was uppermost, the person was allocated to group A. This was done in the presence of, at least, two researchers. Interventions Two types of foot orthosis were made by a member of the research team prior to the randomization and for all the participants. The foot orthoses for group A were custom made using phenolic foam molds of the feet. They consisted of a polypropylene layer of 2 mm from heel to just proximal to the metatarsal heads, an upper sheet of 30 Shore A polyethylene foam, a 5-mm 50 Shore A ethyl vinyl acetate stabilizer element in the heel, and a 30 Shore A subdigital crest made of polyethylene foam. The patients of group B were given a flat placebo insole made of the same material as the upper layer of the foot orthoses used for group A, with the only aim of providing cushioning but not functional control. Both types of foot orthoses were made with the same covering color to reduce the risk of bias. After the final evaluation, the control group received the same type of custom-made foot orthoses given to group A, which were kept throughout the 3 months of the study by the staff of the Clinical Area of Podiatry of the University of Seville, who had no relation with the study. All participants were blinded since they did not know what types of foot orthoses they were given in the study (intervention or placebo). The only information they were given was that the research would evaluate the effectiveness of the foot orthoses to treat pain in patients with rheumatoid arthritis. This procedure is similar to others previously used by other studies (4). The participants were told that the foot orthoses assigned had to be used seven days a week for a minimum of eight hours per day for 3 months. The researcher who performed the measurements at days 0, 30, 60, and 90 (MRB) was not the same researcher who conducted the randomization, adapted the foot orthoses, and gave them to the participants (SPG or MCVB). Thus, they were also blinded. The clinical variables were measured in person at the beginning (baseline) and via phone calls at days 30, 60, and 90. Data collected Clinical and demographic data were collected, including age, gender, weight, height, years of development of the disease, foot pain, foot functionality, foot-related disability, and quality of life. Variables measured were pain, foot functionality, disability, and quality of life. - Pain was measured using the Visual Analogue Scale (10). It ranges from 0 (no pain) to 10 cm (unbearable pain). Pain days were also recorded as the number of days on which the patient felt foot pain in the previous week by assigning a whole number between 0 and 7. - Foot functionality was measured using the Foot Function Index (11). It is a questionnaire with 23 items that are divided into three domains: foot pain, disability, and functional limitation. The values range from 0 and 46, with higher values corresponding to greater pain, disability, and limitation. - Disability related to foot pain was measured using the Manchester Foot Pain and Disability Index(12). The values of this index range from 0 and 100, with higher values corresponding to greater disability. - The SF-12 questionnaire was used to collect data about the quality of life(13), which has values between 0 and 100 with higher values corresponding to lower quality of life. Sample size calculation The minimum sample size was calculated using the following formula to compare mean values between populations: n = 2𝑠2(𝑧𝛼/2 + 𝑧𝛽) 𝑑2, where s2 is the sample variance, α is the type I error, β is the type II error, and d is the minimum difference to be detected. According to previous studies, the variance of the visual analogue scale for pain is equal to 400, and the difference found is 16 (14). Therefore, the following result was obtained: n = 2𝑠2(𝑧𝛼/2 + 𝑧𝛽) 𝑑2 = 2 ∙400 ∙(1.96+0.84)2 162 = 24.5 25 Thus, at least 25 people were needed in each group to compare the mean values. In this study, 68 patients were initially recruited with 34 in each group in consideration of possible losses. Data analysis The analysis of the data was carried out using the statistical software IBM SPSS Statistics 22 ® (IBM, Armonk, NY, USA). The descriptive data provided the mean values and the standard deviations or the absolute frequencies and percentages depending on whether the variables were scalar or categorical. Shapiro-Wilk tests were conducted for the inferential analysis to determine the most appropriate test to use. When data showed a normal distribution by groups, a t-test was carried out for independent samples. The Mann- Whitney’s U test was used for the independent samples when there was no normal distribution. Since the study variables were measured four times, the tests were conducted by pairs for related samples as well. The t-test was used if the variables showed a normal distribution in the four measurements, and the Wilcoxon’s signed-rank test was used for related samples when they did not show a normal distribution. When statistically significant differences were found according to the p-value, the effect size was calculated using Cohen’s d or Rosenthal’s r to analyze the magnitude of the differences. The differences were classified according to the following for both parameters: below 0.2, no effect; 0.2-0.5, small effect; 0.5-0.8, medium effect; above 0.8, large effect (15,16). The confidence level a priori was 95%. RESULTS All the participants who had been measured at the four time points (0, 30, 60 and 90 days) were included in the data analysis. Six people were eventually lost in group A with 28 remaining, and 9 people were lost from group B with 25 remaining. Flow diagram with reasons for exclusion and withdrawal is presented in Figure 1. Demographic data and baseline clinical data across all variables are shown in table 1. The groups were similar in sex distribution, age, body mass, disease duration, Foot Posture Index, and baseline values of pain, disability, and quality of life (P > 0.05). The characteristics are relevant since clinical and demographic factors have been reported to have an influence on the outcomes of customized foot orthoses (17). Table 2 shows all clinical data from all follow-up times. As can be observed, values of all clinical variables, except quality of life (SF-12), got improvement for both groups. However, the only variable that showed significant difference between groups was pain measured with VAS at 90 days (P = 0.048; Cohen’s d = 0.557). Although it must be noted that the difference between pain at baseline and at the last time point of follow-up was 2.5 and 0.56 points in group A and B, respectively. In order to check whether the two types of interventions provided improvement within groups, the evolution of the clinical variables over time were examined (table 3). As can be observed, custom-made foot orthoses produced greater and faster improvement within group A, than cushioning insoles within group B. DISCUSSION The results of this study confirm the published data about the effectiveness of custom-made foot orthoses in rheumatoid arthritis patients since they indicate that the foot orthoses applied in group A produced statistically significant improvement in foot pain. Although there were no significant changes in the remaining clinical variables, in our opinion these findings are important since pain is a frequent symptom in rheumatoid arthritis patients and is strongly related to functionality (17). As rheumatoid arthritis affects around 90% of patients’ feet and has been reported to be an important reason for incapacity in these patients (1), using a non-pharmacological treatment could involve a reduction in drug consumption and thus a decrease in side effects with positive effects on quality of life. Pain was chosen as the main outcome measure in this study because it is the main reason why patients look for treatment (18). This outcome has been widely used in previous studies on the effectiveness of foot orthoses in rheumatoid arthritis (2,4,5,17,19–22). Pain was reduced in both groups. However, group A (custom-made foot orthoses) improved earlier and to a greater extent, demonstrating short-term clinical effectiveness of the foot orthosis as previously reported (21). The only variable that maintained a positive development in the last time point in group B was “foot pain days,” whereas the rest of the 11. Paez-Moguer J, Budiman-Mak E, Cuesta-Vargas AI. Cross-cultural adaptation and validation of the Foot Function Index to Spanish. Foot Ankle Surg. 2014;20(1):34– 9. 12. Gijon-Nogueron G, Ndosi M, Luque-Suarez A, Alcacer-Pitarch B, Munuera PV, Garrow A, et al. Cross-cultural adaptation and validation of the Manchester Foot Pain and Disability Index into Spanish. 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