Quality of life and participation in daily life of adults with Pompe disease receiving enzyme replacement therapy: 10 years of international follow-up

BACKGROUND

Pompe disease is an inheritable metabolic disorder for which enzyme replacement therapy (ERT) has been available since 2006. Effects of ERT have been shown on distance walked, pulmonary function and survival. We investigated whether it also improves quality of life and participation in daily life in adult patients with the disease.

METHODS

In an international survey, we assessed quality of life (Short Form 36, SF-36) and participation (Rotterdam Handicap Scale, RHS) annually between 2002 and 2012. Repeated measurements mixed effects models were used to describe the data over time.

RESULTS

Responses were available for 174 adult patients. In the periods before and after start of ERT, the median follow-up times were 4 years each (range 0.5-8). The SF-36 Physical Component Summary measure (PCS) deteriorated before ERT (-0.73 score points per year (sp/y); CI 95 % -1.07 to -0.39), while it improved in the first 2 years of ERT (1.49 sp/y; CI 0.76 to 2.21), and remained stable thereafter. The Mental Component Summary measure (MCS) remained stable before and during ERT. After declining beforehand (-0.49 sp/year; CI -0.64 to-0.34), the RHS stabilized under ERT.

CONCLUSION

In adult patients with Pompe disease, ERT positively affects quality of life and participation in daily life. Our results reinforce previous findings regarding the effect of ERT on muscle strength, pulmonary function and survival.

A conceptual disease model for adult Pompe disease

Background

Studies in orphan diseases are, by nature, confronted with small patient populations, meaning that randomized controlled trials will have limited statistical power. In order to estimate the effectiveness of treatments in orphan diseases and extrapolate effects into the future, alternative models might be needed. The purpose of this study is to develop a conceptual disease model for Pompe disease in adults (an orphan disease). This conceptual model describes the associations between the most important levels of health concepts for Pompe disease in adults, from biological parameters via physiological parameters, symptoms and functional indicators to health perceptions and final health outcomes as measured in terms of health-related quality of life.

Methods

The structure of the Wilson-Cleary health outcomes model was used as a blueprint, and filled with clinically relevant aspects for Pompe disease based on literature and expert opinion. Multiple observations per patient from a Dutch cohort study in untreated patients were used to quantify the relationships between the different levels of health concepts in the model by means of regression analyses.

Results

Enzyme activity, muscle strength, respiratory function, fatigue, level of handicap, general health perceptions, mental and physical component scales and utility described the different levels of health concepts in the Wilson-Cleary model for Pompe disease. Regression analyses showed that functional status was affected by fatigue, muscle strength and respiratory function. Health perceptions were affected by handicap. In turn, self-reported quality of life was affected by health perceptions.

Conclusions

We conceptualized a disease model that incorporated the mechanisms believed to be responsible for impaired quality of life in Pompe disease. The model provides a comprehensive overview of various aspects of Pompe disease in adults, which can be useful for both clinicians and policymakers to support their multi-faceted decision making.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-015-0334-6) contains supplementary material, which is available to authorized users.

Ten years of the international Pompe survey: patient reported outcomes as a reliable tool for studying treated and untreated children and adults with non-classic Pompe disease

Pompe disease is a rare, progressive lysosomal storage disorder for which enzyme therapy (ERT) became available in 2006. Four years earlier, the IPA/Erasmus MC survey, an international longitudinal prospective survey, was established to collect information on the natural course of the disease and its burden on patients. The survey is a collaboration between Erasmus MC University Medical Center and the International Pompe Association (IPA) and comprises an annual questionnaire that was specifically designed to assess the symptoms and problems of the disease. Here we review our results of over 10 years of follow-up, and discuss the survey's contribution to the field. Tracking 408 Pompe patients between 2002 and 2013, the cumulative data reveals the broad range of clinical manifestations that interfere with patients' lives. The survey allowed us to quantify the rate of disease progression and the positive effects of ERT on patients' quality of life, fatigue, and participation in daily life. Furthermore, it showed for the first time that survival is reduced in adult Pompe disease and improved by ERT. Our results show that a patient survey can serve as a valuable and reliable tool for obtaining quantifiable information on the natural course of a rare disease and on the effects of therapy in a large cohort over a very long time. Most importantly, by working with patient reported outcomes, the survey provides the data that is truly relevant to the patient and complementary to clinical datasets.

Pain: a prevalent feature in patients with mucopolysaccharidosis. Results of a cross-sectional national survey

BACKGROUND

While clinical observations suggest that many patients with mucopolysaccharidosis (MPS) experience chronic pain, few studies have assessed its extent and impact. We therefore investigated its prevalence in patients with all types of MPS in the Netherlands. We also examined the association between pain and health related quality of life (HRQoL) and other clinical variables.

METHODS

We conducted a nationwide MPS survey that used questionnaires on MPS and disease-related symptoms (MPS-specific questionnaire), developmental level (Vineland Screener 0-6 years), quality of life (PedsQl and SF-36), and disability (Childhood Health Assessment Questionnaire). Depending on their age and developmental level, patients or their parents were asked to assess pain by keeping a pain diary for five consecutive days: either the Non-communicating Children's Pain Checklist - Revised (3-18 years intellectually disabled and children <8 years), the VAS-score (> 18 years), or the Faces Pain Scale - Revised (8-18 years).

RESULTS

Eighty-nine MPS patients were invited, 55 of whom agreed to participate (response rate 62 %; median age 10.9 years, range 2.9-47.2 years). They covered a wide spectrum in all age groups, ranging from no pain to severe pain. Forty percent scored above the cut-off value for pain. Most reported pain sites were the back and hips. While the MPS III group experienced the highest frequency of pain (52.9 %), 50 % of patients with an intellectual disability seemed to experience pain, versus 30 % of patients with a normal intelligence. MPS patients scored much lower (i.e., more pain) than a random sample of the Dutch population on the bodily pain domain of the SF-36 scale and the PedsQl.

CONCLUSION

With or without intellectual disabilities, many MPS patients experience pain. We recommend that standardized pain assessments are included in the regular follow-up program of patients with MPS.

Pain in adult patients with Pompe disease: a cross-sectional survey

BACKGROUND

Pompe disease is a rare hereditary metabolic myopathy caused by a deficiency of acid-α-glucosidase. We investigated the presence and severity of pain and its interference with daily activities in a large group of adults with Pompe disease, who we compared with an age-matched control group.

METHODS

Data were collected in a cross-sectional survey in Germany and The Netherlands. Pain was assessed using the short-form brief pain inventory (BPI). Patients also completed the Short Form-36 item (SF-36v2), the Hospital Anxiety and Depression Scale (HADS) and the Rotterdam Handicap Scale (RHS).

RESULTS

Forty-five percent of the 124 adult Pompe patients reported having had pain in the previous 24h, against 27% of the 111 controls (p=0.004). The median pain severity score in Pompe patients reporting pain was 3.1 (on a scale from 0 to 10), indicating mild pain; against 2.6 amongst controls (p=0.06). The median score of pain interference with daily activities in patients who reported pain was 3.3, against 1.3 in controls (p=0.001). Relative to patients without pain, those with pain had lower RHS scores (p=0.02), lower SF-36 Physical and Mental component summary scores (p<0.001 and p=0.049), and higher levels of depression and anxiety (p=0.005 and p=0.003).

CONCLUSIONS

To date, this is one of the largest studies on pain in a specific neuromuscular disorder. Nearly one in two Pompe patients had experienced pain in the previous 24h. Although pain severity and its interference with daily life were mild, pain was related to a reduced quality of life, less participation in daily life, and greater depression and anxiety. Its management should therefore be seen as part of clinical practice involving Pompe patients.

Enzyme replacement therapy and fatigue in adults with Pompe disease

BACKGROUND

Pompe disease is a hereditary metabolic myopathy, for which enzyme replacement therapy (ERT) has been available since 2006. We investigated whether ERT reduces fatigue in adult patients with Pompe disease.

METHODS

In this prospective international observational survey, we used the Fatigue Severity Scale (FSS) to measure fatigue. Repeated measures ANOVA was used to analyze the data over time. In a subgroup of patients, we also evaluated muscle strength using the Medical Research Council Scale, measured pulmonary function as Forced Vital Capacity, and assessed depression using the Hospital Anxiety and Depression Scale.

RESULTS

We followed 163 patients for a median period of 4 years before ERT and for 3 years during ERT. Before ERT, the mean FSS score remained stable at around 5.3 score points; during ERT, scores improved significantly by 0.13 score points per year (p < 0.001). Fatigue decreased mainly in women, in older patients and in those with shorter disease duration. Patients' improvements in fatigue were moderately correlated with the effect of ERT on depression (r 0.55; CI 95% 0.07 to 0.70) but not with the effect of ERT on muscle strength or pulmonary function.

CONCLUSIONS

Fatigue is a common and disabling problem in patients with early and advanced stages of Pompe disease. Our finding that ERT helps to reduce fatigue is therefore important for this patient population, irrespective of the mechanisms underlying this effect.

Impact of enzyme replacement therapy on survival in adults with Pompe disease: results from a prospective international observational study

Background

Pompe disease is a rare metabolic myopathy for which disease-specific enzyme replacement therapy (ERT) has been available since 2006. ERT has shown efficacy concerning muscle strength and pulmonary function in adult patients. However, no data on the effect of ERT on the survival of adult patients are currently available. The aim of this study was to assess the effect of ERT on survival in adult patients with Pompe disease.

Methods

Data were collected as part of an international observational study conducted between 2002 and 2011, in which patients were followed on an annual basis. Time-dependent Cox’s proportional hazards models were used for univariable and multivariable analyses.

Results

Overall, 283 adult patients with a median age of 48 years (range, 19 to 81 years) were included in the study. Seventy-two percent of patients started ERT at some time during follow-up, and 28% never received ERT. During follow-up (median, 6 years; range, 0.04 to 9 years), 46 patients died, 28 (61%) of whom had never received ERT. After adjustment for age, sex, country of residence, and disease severity (based on wheelchair and ventilator use), ERT was positively associated with survival (hazard ratio, 0.41; 95% CI, 0.19 to 0.87).

Conclusion

This prospective study was the first to demonstrate the positive effect of ERT on survival in adults with Pompe disease. Given the relatively recent registration of ERT for Pompe disease, these findings further support its beneficial impact in adult patients.

Severely impaired health status at diagnosis of Pompe disease: a cross-sectional analysis to explore the potential utility of neonatal screening

Since the introduction of enzyme replacement therapy for Pompe disease, awareness and early diagnosis have gained importance. Because the therapy is most effective when started early and methods for dried bloodspot screening for Pompe disease are currently being explored, neonatal screening is getting increased attention. The objective of this study was to investigate the gains that might be achieved with earlier diagnosis by neonatal screening. For this purpose we analyzed the health and functional status of non-screened patients with Pompe disease at the time of diagnosis. Previously collected clinical data and results of an international patient-reported questionnaire were used. Cross-sectional data of 53 patients with Pompe disease diagnosed between 1999 and 2009 (aged 0-64 years) were analyzed. According to the World Health Organization's International Classification of Functioning, Disability and Health the following domains are described: body function, activity, participation and contextual factors. In all patients with classic infantile Pompe disease cardiac function, hearing, muscle strength and motor development were considerably impaired at the time of clinical diagnosis. The use of oxygen and/or nasogastric tube-feeding was reported in more than 70% of these cases. Most children, adolescents and adults had advanced muscle weakness and impaired respiratory function at the time of their diagnosis, causing varying degrees of handicap. About 12% of them used a walking device and/or respiratory support at the time of diagnosis. The severely impaired health status reported here provides a strong argument for earlier diagnosis and to further explore the potential of neonatal screening for Pompe disease.

Survival and associated factors in 268 adults with Pompe disease prior to treatment with enzyme replacement therapy

BACKGROUND

Pompe disease is a rare lysosomal storage disorder characterized by muscle weakness and wasting. The majority of adult patients have slowly progressive disease, which gradually impairs mobility and respiratory function and may lead to wheelchair and ventilator dependency. It is as yet unknown to what extent the disease reduces the life span of these patients. Our objective was to determine the survival of adults with Pompe disease not receiving ERT and to identify prognostic factors associated with survival.

METHODS

Data of 268 patients were collected in a prospective international observational study conducted between 2002 and 2009. Survival analyses from time of diagnosis and from time of study entry were performed using Kaplan-Meier curves and Cox-proportional-hazards regression.

RESULTS

Median age at study entry was 48 years (range 19-79 years). Median survival after diagnosis was 27 years, while median age at diagnosis was 38 years. During follow-up, twenty-three patients died prior to ERT, with a median age at death of 55 (range 23-77 years). Use of wheelchair and/or respiratory support and patients' score on the Rotterdam Handicap Scale (RHS) were identified as prognostic factors for survival. Five-year survival for patients without a wheelchair or respiratory support was 95% compared to 74% in patients who were wheelchair-bound and used respiratory support. In a Dutch subgroup of 99 patients, we compared the observed number of deaths to the expected number of deaths in the age- and sex-matched general population. During a median follow-up of 2.3 years, the number of deaths among the Dutch Pompe patients was higher than the expected number of deaths in the general population.

CONCLUSION

Our study shows for the first time that untreated adults with Pompe disease have a higher mortality than the general population and that their levels of disability and handicap/participation are the most important factors associated with mortality. These results may be of relevance when addressing the effect of ERT or other potential treatment options on survival.