The effect of scoliosis surgery on pulmonary function in spinal muscular atrophy type II patients.

PURPOSE: Various results of the previous literature related to surgical effect on pulmonary function of spinal muscular atrophy (SMA) patients might be due to different SMA type, different fusion level and technique. The aim of this study was to determine the value of scoliosis surgery for SMA type II patients with regard to pulmonary function, under the same fusion level, fusion technique and average long-term follow-up. METHODS: Ten SMA II patients who underwent spinal correction procedures from 1993 to 2010 were identified. Data on clinical features and pulmonary function, including forced vital capacity (FVC) and forced expiratory volume in 1st second (FEV1), were collected. The data on pulmonary function were divided into preoperative, postoperative short-term (0-5 years), mid-term (5-10 years), and long-term (>10 years). Statistical comparisons were made using the Wilcoxon test for pulmonary function and body weight analysis. Questions were answered by parents on how surgery influenced the frequency of respiratory infection and the ability to sit at school. RESULTS: The average length of postoperative pulmonary function follow-up was 12.3 years (range 4.9-15.9 years). There was no significant difference in FVC or FEV1 between preoperative and each postoperative period. However, a significant decline from mid-term to long-term was observed (p = 0.028). Body weight increased significantly in all postoperative periods and was moderately correlated to pulmonary function (r = 0.526 for FVC). The answers to the questionnaire revealed that 80% of the patients had obvious improvement in the frequency of respiratory infection and 100% were tolerable sitting at school. CONCLUSIONS: Surgical correction for scoliosis in SMA II patients results in pulmonary function being maintained during long-term follow-up. In addition, the advantages of surgery also include body weight gain, better sitting tolerance, and reduced frequency of respiratory infection.

Confirmatory Factor Analysis of the Boston Carpal Tunnel Questionnaire.

PURPOSE: Carpal tunnel syndrome (CTS) is one of the most common hand problems and a major cause of work disability. The purpose of this study was to use confirmatory factor analysis (CFA) to assess the factor structure of the Boston Carpal Tunnel Questionnaire (BCTQ) in patients with CTS. METHODS: One hundred and twenty-three patients with CTS were recruited from two hospitals. Each patient completed the functional status scale and the symptom severity scale of the BCTQ. CFA was used to assess the model fit between the data and pre-established theoretical measurement models. RESULTS: CFA showed that all three-factor models were better than the original two-factor model. Among the three-factor models, the simplified model, with 11 items assessing daytime pain, nocturnal numbness/tingling, and hand function was the best, for the model fit the data better than did the other models. Specifically, the Comparative Indices were larger than 0.95 (Tucker-Lewis Index and Comparative Fit Index values), and the Absolute Fit Indices and information-theoretic measures were the smallest. Moreover, all factor loadings were significant and high in magnitude (ranging from 0.66 to 0.99), the composite reliabilities exceeded 0.60 (ranging from 0.78 to 0.94), and the average variance extracted exceeded 0.50 (ranging from 0.61 to 0.89). CONCLUSION: The simplified model showed the highest reliability and validity, and the factor structure was the simplest/clearest one. The simplified model is recommended for clinical use due to its convenience and precision for assessing the problems of patients with CTS.

Validation of the Chinese version of the Boston Carpal Tunnel Questionnaire.

PURPOSE: Carpal tunnel syndrome (CTS) is a common diagnosis occurring in the workplace when people experience hand or wrist symptoms and difficulty performing activities. This study aimed to investigate the psychometric properties of the Chinese version of the Boston Carpal Tunnel Questionnaire (BCTQ) used to evaluate patients with CTS. METHODS: A convenience sample of patients with CTS was recruited from two hospitals. The Symptom Severity Scale (SSS) and Functional Status Scale (FSS) of the BCTQ were used to assess symptoms and functional status. Test-retest reliability within 1 week was evaluated (n = 51). Construct validity was assessed by examining the relationship between the BCTQ and other well known measures (n = 99). Responsiveness of the scale was examined pre- and post-operatively for patients undergoing carpal tunnel surgery (n = 23). RESULTS: High reliability was demonstrated through intraclass correlation coefficients of 0.81 and 0.83 for SSS and FSS, respectively. The minimal detectable change was 0.86 and 0.75 for SSS and FSS, respectively. Convergent validity was supported by high correlation of both scales with Disability of the Arm, Shoulder and Hand (|rho| = 0.63, 0.75 for SSS and FSS), and moderate to high correlation with the subscales of the Short-Form 36 for SSS(|rho| = 0.72 for Body Pain) and FSS (|rho| = 0.48 for Physical Function). Responsiveness was confirmed by moderate to high standardized response means for SSS (1.03) and FSS (0.62). CONCLUSION: The Chinese BCTQ is a reliable, valid and responsive disease-specific measure for assessment of symptoms and functional status in patients with CTS.

Changes of muscle mechanics associated with anterior cruciate ligament deficiency and reconstruction.

Isometric and isokinetic knee strength deficits were examined on patients with anterior cruciate ligament (ACL) injury before and after ACL reconstruction. Muscle strengths of the uninjured and injured knees were measured from an ACL injured (n = 12) and a control (n = 15) group. Five isometric (10, 30, 50, 70, and 90° of knee flexion) and 5 isokinetic (50, 100, 150, 200, and 250°·s) strengths of quadriceps and hamstrings were measured prereconstruction and postreconstruction (3 and 6 months). Compared with the controls, the uninjured knee showed normal strength and patterns of length-tension and force-velocity relationships. Compared with the uninjured knee, the injured knees showed a generally 25-30% decrease in quadriceps and hamstrings strength with normal patterns of length-tension and force-velocity relationships. By 3 months of reconstruction, weakness of quadriceps of the injured knees was exacerbated, particularly at lengthened positions (∼ 40% of the uninjured knees at knee flexion 70 and 90°) and at slower velocities (∼35% of the uninjured knees at the 50 and 100°·s, p < 0.05), with flattened patterns of mechanical output. By 6 months of reconstruction, the quadriceps of the injured knees still showed significant weakness (∼50% of the uninjured knees) in both contraction types (isometric at knee flexion 90° and isokinetic at 50°·s, p < 0.05). The hamstrings of the injured knees had not shown significant changes after reconstruction. A strengthening program placing emphasis on greater knee flexion angles and slower movement speed with sufficient training duration post ACL reconstruction is recommended because of long-lasting and exacerbated weakness during 3 and 6 months postreconstruction.

Measurement precision of the disability for back pain scale-by applying Rasch analysis.

BACKGROUND: The Oswestry Disability Index (ODI) is widely used for patients with back pain. However, few studies have examined its psychometric properties using modern measurement theory. The purpose of this study was to investigate the psychometric properties of the ODI in patients with back pain using Rasch analysis. METHODS: A total of 408 patients with back pain participated in this cross-sectional study. Patients were recruited from the orthopedic, neurosurgery, rehabilitation departments and pain clinic of two hospitals. Rasch analysis was used to examine the Chinese version of ODI 2.1 for unidimensionality, item difficulty, category function, differential item functioning, and test information. RESULTS: The fit statistics showed 10 items of the ODI fitted the model's expectation as a unidimensional scale. The ODI measured the different levels of functional limitation without skewing toward the lower or higher levels of disability. No significant ceiling and floor effects and gaps among the items were found. The reliability was high and the test information curve demonstrated precise dysfunction estimation. CONCLUSIONS: Our results showed that the ODI is a unidimensional questionnaire with high reliability. The ODI can precisely estimate the level of dysfunction, and the item difficulty of the ODI matches the person ability. For clinical application, using logits scores could precisely represent the disability level, and using the item difficulty could help clinicians design progressive programs for patients with back pain.

Pre- and Post-Operative Education and Health-Related Quality of Life for Patients with Hip/Knee Replacement and Hip Fracture.

Arthroplasty for the hip/knee and surgeries for hip fractures are increasing worldwide. The aims of this study were to investigate changes in health-related quality of life (HRQOL) after surgery with an early mobility education program, and to explore their associations with pain and anxiety. Pain intensity and anxiety were assessed with the visual analogue scale (VAS) and Beck Anxiety Inventory (BAI), and HRQOL was assessed with the Short Form-36 (SF-36). The physical component summary (PCS) and mental component summary (MCS) and eight subscales of the SF-36 were calculated. At pre-operation, the patients suffered from moderate pain and mild anxiety, and their HRQOL scores were low (4.9, 7.8, 35.4, and 48.2 for the VAS, BAI, PCS, and MCS, respectively). The pain, anxiety, and HRQOL improved after surgery and had moderate to large effect sizes at 6-month follow-up (Glass's delta = 1.23, 0.88, 0.81, and 0.67 for VAS, BAI, PCS, and MCS, respectively). Pain and anxiety were strongly correlated to HRQOL at each stage, with the maximum correlation (r = -0.34 to -0.93) reached at 6-month follow-up. The surgery effectively improves HRQOL, as the reduced pain and anxiety lead to better physical and mental HRQOL.

A cross-sectional study of disability and quality of life in patients with low back pain: Focus on sex and gender.

BACKGROUND: Sex and gender affect responses to pain, but little is known about disability and quality of life. OBJECTIVES: To investigate the effects of sex and gender on disability and health-related quality of life (HRQOL) in patients with low back pain. METHODS: Ninety-three patients with low back pain were included in this cross-sectional survey study. Disability, HRQOL and gender identity were respectively assessed with the Oswestry Disability Index, Short Form-36 and Bem Sex Role Inventory. The participants were classified into four gender role orientations (masculinity, femininity, androgyny and undifferentiated). One-way analysis of variance was used to analyze both the sex and the gender role orientation. RESULTS: Females had higher disability than males (p< 0.05), but in gender identity, no significant difference was found. Seven domains of HRQOL were lower than the healthy norms. Males experienced greater impacts than females on vitality and mental health (p< 0.05). For gender identity, five domains of HRQOL had significant differences (p< 0.05). Masculinity orientation had the least impact on four domains (p< 0.05), while undifferentiated orientation had the largest impact on all domains. CONCLUSION: Sex and gender effects can be used to analyze disability and HRQOL in patients with low back pain. Females have higher disability, while HRQOL is greatly influenced by different gender role orientations.

The relative and absolute reliability of leg muscle strength testing by a handheld dynamometer.

To examine the relative and absolute interrater reliability of handheld dynamometers (HHD) for assessing the lower extremity muscle strength, maximal voluntary contractions (MVCs) of 16 young adults for bilateral hip and knee muscles were tested using the break method. Three MVCs of each muscle group were required for obtaining the muscle strength. Participants' muscle strengths were tested by 2 raters. The intraclass correlation coefficients (ICCs) and the smallest real differences (SRD) were used to examine the relative and absolute reliabilities, and the Bland-Altman analyses were used to check whether systematic bias exists. The results showed that the relative reliabilities of all muscle groups were excellent (ICCs = 0.83-0.92) except for the knee extensors (ICC = 0.60). The SRD represents the smallest difference that indicates a real change for a single subject. The SRD% of all muscle groups was acceptable (ranging from 8.4 to 22.8 %), with the hip extensors being the smallest and knee extensors being the largest. The reliability of the knee extensors was unsatisfactory because of poor relative and absolute reliabilities and systematic bias. In addition to assessing the relative reliability in strength measurement, the absolute reliability provides the data of the measurement error, which is useful information in clinical practice to know whether the change in strength of a subject is real. Hand-held dynamometer is a reliable tool for quantifying most of the hip and knee strength except for the knee extensors. Modifying the measuring technique for knee extension is needed in future studies to improve the reliability.

Measurement of the functional status of patients with different types of muscular dystrophy.

Muscular dystrophy (MD) comprises a group of diseases characterized by progressive muscle weakness that induces functional deterioration. Clinical management requires the use of a well-designed scale to measure patients' functional status. This study aimed to investigate the quality of the functional scales used to assess patients with different types of MD. The Brooke scale and the Vignos scale were used to grade arm and leg function, respectively. The Barthel Index was used to evaluate the function of daily living activity. We performed tests to assess the acceptability of these scales. The characteristics of the different types of MD are discussed. This was a multicenter study and included patients diagnosed with Duchenne muscular dystrophy (DMD) (classified as severely progressive MD), Becker muscular dystrophy (BMD), limb girdle muscular dystrophy (LGMD) and facioscapulohumeral muscular dystrophy (FSHD). BMD, LGMD, and FSHD were classified as slowly progressive MD. The results demonstrated that the Brooke scale was acceptable for grading arm function in DMD, but was unable to discriminate between differing levels of severity in slowly progressive MD. The floor effect was large for all types of slowly progressive MD (range, 20.0-61.9), and was especially high for BMD. The floor effect was also large for BMD (23.8%) and FSHD (50.0%) using the Vignos scale. Grades 6-8 of the Vignos scale were inapplicable because they included items involving the use of long leg braces for walking or standing, and some patients did not use long leg braces. In the Barthel Index, a ceiling effect was prominent for slowly progressive MD (58.9%), while a floor effect existed for DMD (17.9%). Among the slowly progressive MDs, FSHD patients had the best level of functioning; they had better leg function and their daily living activities were less affected than patients with other forms of slowly progressive MD. The results of this study demonstrate the acceptability of the different applications used for measuring functional status in patients with different types of MD. Some of the limitations of these measures as applied to MD should be carefully considered, especially in patients with slowly progressive MD. We suggest that these applications be used in combination with other measures, or that a complicated instrument capable of evaluating the various levels of functional status be used.

Influence of testing position on the reliability of hip extensor strength measured by a handheld dynamometer.

Hip extensors belong to an important muscle group that controls standing, walking and other functional activities. The prone position (PP) is commonly used to measure the strength of the hip extensors; however, the reliability of such measurements is poor. The aim of this study was to determine the effect of different testing positions, that is, the PP and the prone standing position (PSP), on the reliability of measurements of hip extensor strength. Intrasession reliability and interrater reliability studies were performed on 47 and 16 normal subjects, respectively. The muscle strength of the hip extensors was tested in both the PP and PSP. A handheld dynamometer and break test were used to measure the strength. Relative reliability and absolute reliability were assessed in both PP and PSP. For relative reliability, the intraclass correlation coefficient (ICC) was used to examine the level of reproducibility among measurements. Absolute reliability, the smallest real difference (SRD), was used to provide information on measurement error. The results showed that the reliability was better in PSP than in PP. For relative reliability, the values of ICCs were excellent in the intrasession reliability study, in both PP (ICC1,3 = 0.92) and PSP (ICC1,3 = 0.94). However, the interrater reliability was only excellent in PSP; the ICC2,3 were 0.92 in PSP and 0.65 in PP. For absolute reliability, the values of the SRD were much lower in PSP (29.8) than in PP (71.8), indicating that the measurement of muscle strength in PSP was more stable and had smaller measurement error than in PP. Changing the testing position from the traditional "prone" to "prone-standing" effectively improved both the relative reliability and the absolute reliability.

Treatment for frozen shoulder combined with calcific tendinitis of the supraspinatus.

Calcific tendinitis of the shoulder is a process that involves calcium deposition in the rotator cuff tendons. It is usually a self-limiting process and is often chronic in nature. However, it can lead to acute pain resulting in frozen shoulder syndrome. We report 32 cases in which frozen shoulder was associated with calcific tendinitis of the supraspinatus. The aim of this study was to use arthroscopic brisement of the glenohumeral joint and make multiple punctures in the calcific spot to treat the frozen shoulder associated with calcific tendinitis of the supraspinatus. In our study, 30 patients had satisfactory results after a 2-year follow-up. Five patients experienced some postoperative calcium shadows, but there was also greater improvement in the range of motion and pain relief in this study compared with other reports in the literature of frozen shoulder cases.

Factors affecting the health-related quality of life of caregivers of patients with muscular dystrophy.

Muscular dystrophy (MD) is a group of progressive muscle weakness diseases. The caregiver burden, increasing as the disease progresses, can be associated with impaired health-related quality of life (HRQOL). The aims of this study were to investigate the HRQOL in caregivers of patients with MD and identify the factors associated with HRQOL. A cross-sectional assessment of caregiver HRQOL was performed with the Short Form-36 and compared with norms. The factors affecting HRQOL were investigated by patient and caregiver characteristics. The Muscular Dystrophy Functional Rating Scale was used to assess the functional status (mobility, basic activities of daily living, arm function, and impairment) of patients. The demographic data and social interaction activities of caregivers were assessed. Caregivers (n = 62) had poor HRQOL. Caregiver HRQOL was associated with the patient's functional status, especially in the domains of Vitality and Mental Health. Numerous visits by neighbors and close friends of the caregiver family indicated better HRQOL (in the body pain, general health, vitality, role emotion and mental health domains). Caregiver HRQOL was associated with caregiver education level, while patient age, caregiver age, length of caregiving, and family income were not. These findings demonstrate that caregivers have poor HRQOL, and the mental domain of quality of life is associated with the patient's functional status, social interaction, and caregiver education level. We suggest that rehabilitation programs focus on caregiver HRQOL, promote the patient's functional status with assistive technology, enhance professional caring techniques, and encourage participation in social groups to improve caregiver HRQOL.

The psychometric properties of the cervical nonorganic signs in patients with neck pain: an assessment of pain expression.

PURPOSE: Neck pain is a common cause of disability. This study investigated the psychometric properties of the cervical nonorganic signs (CNOS), a tool for assessing abnormal illness behaviors in patients with neck pain. METHODS: The CNOS was administered on patients with neck pain. Reliability and validity analyses were used to evaluate the psychometric properties. Exploratory factor analysis was used to investigate the dimensionality. Correlations with the Short Form-36 were used to investigate the convergent validity. RESULTS: The results supported the reliability (inter-rater reliability intra-class correlation: 0.920), validity (correlated with body pain (|ρ|=0.31) and vitality (|ρ| =0.30), and two-factor dimensionality (χ2= 5.904, p= 0.66; χ2/df = 0.738; RMSEA< 0.001; CFI = 1.000; TLI = 1.024; SRMR = 0.047) of the scale. The two factors were pain (severe pain) and vitality (poor vitality) expressed by the patients. CONCLUSION: The CNOS is a reliable and valid instrument for assessing pain and vitality problems. It helps patients to express severe pain and lack of vitality. The rehabilitation discipline could use the scale to understand pain expression and to design proper rehabilitation programs. Implications for Rehabilitation The cervical nonorganic signs has two domains (pain and vitality). The scale is reliable and valid for patients with neck pain. Patients with high scores on the pain domain have severe body pain that may interfere with normal social activities. Clinicians should understand their suffering and try to help them to alleviate the pain.

Development and Validation of Taiwanese Version of the Neck Disability Index.

STUDY DESIGN: Cross-cultural adaptation and cross-sectional psychometric testing in a convenience sample of patients with neck pain. OBJECTIVE: To translate and cross-culturally adapt the Neck Disability Index (NDI) into a Taiwanese version and to assess the psychometric properties. SUMMARY OF BACKGROUND DATA: The Taiwanese NDI has not been developed or validated. METHODS: The NDI was first translated and culturally adapted to the Taiwanese version. The test-retest reliability within 1 week was examined (n = 32). The factor structure was assessed by confirmatory factor analysis (n = 137). The construct validity was assessed by examining the relationship between the NDI and other well-known measures (n = 137). RESULTS: The Taiwanese version was successfully translated and cross-culturally adapted. The internal consistency was excellent, with Cronbach α = 0.89. High test-retest reliability was demonstrated with intraclass correlation coefficients of 0.87. The minimal detectable change was 8.74. The two-factor model (pain and function factors) was better than the one-factor model, with higher factor loadings and better goodness-of-fit statistics. The convergent validity was supported by moderate correlation of the pain factor with the Visual Analogue Scale (|rho| = 0.45), and high correlation of the function factor with the physical component summary of the Short-From 36 (SF-36) (|rho| = 0.60). CONCLUSION: The Taiwanese NDI is a reliable and valid disease-specific measure for assessment of pain and functional status in patients with neck pain. LEVEL OF EVIDENCE: 3.

Quality of life of patients with Duchenne muscular dystrophy: from adolescence to young men.

PURPOSE: This study investigated quality of life (QOL) in adolescent and young men with Duchenne muscular dystrophy (DMD). METHODS: Health-related QOL and global QOL were assessed with the Short Form 36 (SF-36) and World Health Organization Quality of Life-BREF (WHOQOL-BREF). Associations between functional status and QOL were assessed. RESULTS: All domains of the SF-36 were below Taiwan norms (effect size: -14.2 to -0.5), especially Physical Function, Role Physical, and Social Function. Three of the four domains of the WHOQOL-BREF were below Taiwan norms (effect size: -2.0 to -0.7). The Physical Function of the SF-36 was moderately correlated with functional status (mobility, basic activities of daily living, and arm function). The Social Function of the SF-36 and Social Relationships of the WHOQOL-BREF were also moderately correlated with functional status (impairment, basic activities of daily living, and arm function). CONCLUSION: The adolescent and young men with DMD had poor health-related and global QOL. Poor QOL was related to both physical condition and social health. We suggest that rehabilitation programs focus on using assistive devices to facilitate arm function and encouraging participation in social activities to improve the QOL of patients with DMD. Implications for rehabilitation Duchenne muscular dystrophy (DMD) is a progressive muscle weakness disease that not only impacts physical health but also leads to poor quality of life in many domains. A valuable rehabilitation goal for patients with DMD is to encourage participation in social activities. Medical care and educational programs should plan a formal transition processes for patients with DMD from pediatric to adult care to maximum their quality of life. Arm function is associated with many domains of global quality of life, so a key element in improving quality of life may be to improve arm function.

Correlations between quality of life and psychological factors in patients with chronic neck pain.

The purpose of this study was to investigate health-related quality of life (HRQOL) and associated factors in patients with chronic neck pain (CNP). The HRQOL of patients with CNP was assessed by the Short Form-36 questionnaire in this cross-sectional study. To evaluate the psychological factors related to HRQOL, the Eysenck Personality Questionnaire, Chinese Health Questionnaire, and Beck Anxiety Inventory were used. The scores for the eight subscales of Short Form-36 were all lower than the Taiwanese age-matched normative values (p < 0.001). The two most strongly affected subscales were the role-physical subscale and the bodily pain subscale; both scores were below half the score of the age-/sex-matched normative values. The physical components summary score, a summary measure, was moderately correlated with age (rho = -0.43), education level (rho = 0.37) and Beck Anxiety Inventory score (rho = -0.36). The mental components summary score was moderately to highly correlated with the Chinese Health Questionnaire score (rho = -0.72), the neuroticism domain of Eysenck Personality Questionnaire (rho = -0.52) and Beck Anxiety Inventory score (rho = -0.41). The HRQOL of patients with CNP was worse than that of normal subjects across all domains. Furthermore, patients with a neurotic personality, minor psychiatric morbidity and higher anxiety status showed poor mental health, as measured by the Short Form-36. We found that patients with CNP had multiple physical and mental health problems in terms of. The mental health of patients with CNP was strongly associated with various psychological factors. Comprehensive assessment of the physical and mental functioning of patients with CNP can improve the management and care of these patients.

Development of a Chinese version of the Oswestry Disability Index version 2.1.

STUDY DESIGN: Cross-cultural adaptation and cross-sectional psychometric testing in a convenience sample of patients with low back pain. OBJECTIVE: To translate and culturally adapt the Oswestry Disability Index version 2.1 (ODI 2.1) into a Mandarin Chinese version and to assess its reliability and validity. SUMMARY OF BACKGROUND DATA: The Chinese ODI 2.1 has not been developed and validated. METHODS: The ODI 2.1 was translated and culturally adapted to the Chinese version. The validity of the translated Chinese version was assessed by examining the relationship between the ODI and other well-known measures. Test-retest reliability was examined in 52 of these patients, who completed a second questionnaire within 1 week. RESULTS: Internal consistency of the ODI 2.1 was excellent with Cronbach's alpha = 0.903. The intraclass correlation coefficient of test-retest reliability was 0.89. The minimal detectable change was 12.8. The convergent validity of the Chinese ODI is supported by its high correlation with other physical functional status measures (Roland Morris Disability Questionnaire and SF-36 physical functioning subscale, r = 0.76 and -0.75, respectively), and moderate correlation with other measures (Visual Analogue Scale, r = 0.68) and certain SF-36 subscales (role-physical, bodily pain, and social functioning, r range: -0.49 to -0.57). As expected, the ODI was least correlated with nonfunctional measures (SF-36 mental subscale and role-emotional subscale, r = -0.25 and -0.33, respectively). CONCLUSION: The results of this study indicate that the Chinese version of the ODI 2.1 is a reliable and valid instrument for the measurement of functional status in patients with low back pain.

Development and validation of a muscular dystrophy-specific functional rating scale.

OBJECTIVE: To develop a reliable and valid new rating scale for measuring the functional impact of muscular dystrophy. DESIGN: Prospective and longitudinal investigation. SETTING: Three academic medical centres in Taiwan and the Muscular Dystrophy Association of Taiwan. MEASURES: The Brooke Scale, the Vignos Scale, the Barthel Index, muscular strength, contracture severity, and predicted forced vital capacity (FVC%). METHODS: Scale development was in three stages. In stage I, a preliminary pool of 53 items was generated from patient interviews (n = 25), literature review, existing functional rating scales and expert opinion. In stage II, these items were administered to 85 patients with muscular dystrophy. The resulting data were analysed to construct a rating scale (the Muscular Dystrophy Functional Rating Scale, MDFRS) that encompassed four unidimensional constructs: mobility, basic activities of daily living, arm function and impairment. In stage III, the measurement properties of this rating scale were assessed in 121 muscular dystrophy patients different from those examined with the preliminary instrument. RESULTS: Internal consistency reliability was excellent for all domains of the final 33-item scale, with values of Cronbach's alpha ranging from 0.84 to 0.97. Intraclass correlation coefficients for test-retest and inter-rater reliability were 0.99 for all domains of the MDFRS. The MDFRS showed moderate to high correlations with a range of functional rating scales measuring similar aspects and impairment parameters (Spearman's rho = 0.65-0.91; P < 0.001, each). Confirmatory factor analysis supported a unitary construct of the four-dimensional MDFRS. The MDFRS had small floor and ceiling effects in the study samples. Sensitivity to change was confirmed by large standardized response means for the MDFRS total score. CONCLUSIONS: The MDFRS is a reliable and valid disease-specific measure of functional status for patients with muscular dystrophy.