Psychometric performance of the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA) in a randomized, double-blind, placebo-controlled crossover study in subjects with mitochondrial disease

BACKGROUND

The Primary Mitochondrial Myopathy Symptom Assessment (PMMSA) is a 10-item patient-reported outcome (PRO) measure designed to assess the severity of mitochondrial disease symptoms. Analyses of data from a clinical trial with PMM patients were conducted to evaluate the psychometric properties of the PMMSA and to provide score interpretation guidelines for the measure.

METHODS

The PMMSA was completed as a daily diary for approximately 14 weeks by individuals in a Phase 2 randomized, placebo-controlled crossover trial evaluating the safety, tolerability, and efficacy of subcutaneous injections of elamipretide in patents with mitochondrial disease. In addition to the PMMSA, performance-based assessments, clinician ratings, and other PRO measures were also completed. Descriptive statistics, psychometric analyses, and score interpretation guidelines were evaluated for the PMMSA.

RESULTS

Participants (N = 30) had a mean age of 45.3 years, with the majority of the sample being female (n = 25, 83.3%) and non-Hispanic white (n = 29, 96.6%). The 10 PMMSA items assessing a diverse symptomology were not found to form a single underlying construct. However, four items assessing tiredness and muscle weakness were grouped into a "general fatigue" domain score. The PMMSA Fatigue 4 summary score (4FS) demonstrated stable test-retest scores, internal consistency, correlations with the scores produced by reference measures, and the ability to differentiate between different global health levels. Changes on the PMMSA 4FS were also related to change scores produced by the reference measures. PMMSA severity scores were higher for the symptom rated as "most bothersome" by each subject relative to the remaining nine PMMSA items (most bothersome symptom mean = 2.88 vs. 2.18 for other items). Distribution- and anchor-based evaluations suggested that reduction in weekly scores between 0.79 and 2.14 (scale range: 4-16) may represent a meaningful change on the PMMSA 4FS and reduction in weekly scores between 0.03 and 0.61 may represent a responder for each of the remaining six non-fatigue items, scored independently.

CONCLUSIONS

Upon evaluation of its psychometric properties, the PMMSA, specifically the 4FS domain, demonstrated strong reliability and construct-related validity. The PMMSA can be used to evaluate treatment benefit in clinical trials with individuals with PMM. Trial registration ClinicalTrials.gov identifier, NCT02805790; registered June 20, 2016; https://clinicaltrials.gov/ct2/show/NCT02805790 .

Development and content validity of the Barth Syndrome Symptom Assessment (BTHS-SA) for adolescents and adults

Background

Barth Syndrome (BTHS) is a rare genetic disorder that presents as a complex of debilitating symptoms and reduced life expectancy. Well-developed, BTHS-specific assessments measuring primary signs and symptoms of BTHS are not currently available, making it difficult to evaluate treatment effects in BTHS clinical studies. The objective of this research was to develop symptom-focused patient-reported outcome (PRO) measures for use in clinical studies with adolescents and adults with BTHS.

Methods

Concept elicitation interviews (CEIs) with pediatric (n = 18, age < 16 years) and adult (n = 15, age ≥ 16 years) individuals with BTHS and/or their caregivers were conducted to identify signs and symptoms relevant to BTHS and important to individuals with the condition. Based on CEI results, questionnaire construction activities were conducted to create unique adolescent and adult versions of the Barth Syndrome-Symptom Assessment (BTHS-SA). The questionnaires were evaluated in cognitive debriefing interviews (CDIs) with adolescents (n = 12; age 12- < 16 years) and adults (n = 12; age ≥ 16 years) with BTHS to assess relevance and readability of the tools.

Results

During the CEIs, a total of 48 and 40 signs and symptoms were reported by the pediatric and adult groups, respectively; 31 were reported by both age groups. Fatigue/tiredness and muscle weakness were the symptoms most frequently reported by both pediatric and adult patients with BTHS as important to improve with an effective treatment. The CEI results informed construction of a nine-item version of the BTHS-SA for adolescents and an eight-item version for adults. Developed for daily administration, each version asks respondents to rate symptom severity “at its worst” over the 24 h prior to administration. CDIs with both adolescents and adults with BTHS demonstrated that each BTHS-SA version was reflective of the disease experience and that respondents could interpret the questionnaire as intended and provide responses that accurately reflected their symptom experience.

Conclusions

The BTHS-SA adolescent and adult versions are content-valid PRO measures that can be used to evaluate severity of disease-specific symptoms in future clinical trials. Given the lack of available and well-developed assessments in this underserved therapeutic area, these tools fulfill a need for clinical researchers developing treatments for individuals with BTHS.

Pharmacokinetics, safety, and tolerability of ceftolozane/tazobactam in healthy Japanese, Chinese, and white subjects

Ceftolozane/tazobactam, a novel antibacterial with potent activity against Gram-negative pathogens, was developed for treatment of complicated urinary tract infections, including pyelonephritis, and intra-abdominal infections. A phase 1 pharmacokinetic (PK) study of ceftolozane/tazobactam in healthy Japanese, Chinese, and white volunteers was conducted to assess the potential effect of ethnicity on PK. The PK of ceftolozane, tazobactam, and tazobactam metabolite M1 was compared after single 1.5- and 3-g intravenous doses of ceftolozane/tazobactam. Ten Japanese, nine Chinese, and ten white subjects were enrolled, and 27 completed all doses of study medication. Dose-normalized PK parameters for ceftolozane and tazobactam were similar among Japanese, Chinese, and white subjects (at 1.5-g and 3-g doses, ceftolozane area under the plasma concentration-time curve from zero to infinity [AUC_0-∞ ] = 166.3, 165.9, and 185.5 h μg/mL, respectively, and 157.7, 158.5, and 181.2 h μg/mL, respectively; tazobactam AUC_0-∞ = 48.5, 43.2, and 50.1 h μg/mL, respectively, and 47.3, 43.7, and 50.0 h μg/mL, respectively. The 90% CIs of their ratio estimates were within the range 0.80 to 1.25 with the exception of AUC_0-∞ for ceftolozane after the 3-g dose (0.79). The cumulative amount of ceftolozane and tazobactam excreted in urine was similar among ethnic groups. For all groups, treatment-emergent adverse events (AEs) were mild; no deaths or serious AEs were reported. The PK of ceftolozane/tazobactam was approximately dose proportional (i.e. doubling the dose approximately doubles the exposure) and similar among the groups. No dosage adjustment is needed for ceftolozane/tazobactam in Japanese and Chinese patients.