Thanks to better treatment strategies the prognosis of GSD I has markedly improved within the last decades, and many patients reach adulthood without major complications. Nevertheless, GSD I remain challenging disorders as treatment requires meticulous adherence and planning with high impact on daily life and QoL. Only little research has been performed on this topic in the past. This is especially true for adults with this rare metabolic disorder. We herein report data on the impact of GSD I on different aspects of adult life and perceived disease burden in 34 GSD I patients.
In most previous studies, QoL has been addressed with the use of standardized questionnaires: Storch et al. investigated psychosocial functioning of children with GSD Ia and Ib [12]. The authors studied 31 children and their parents using different questionnaires that addressed QoL, loneliness, family functioning, sibling relationship quality, parental distress, parenting stress, child adaptive behaviour, and child emotional and behavioural functioning. The authors showed that both types of GSD I were associated with reduced QoL and independent functioning, elevated levels of internalizing distress and parental stress relative to healthy peers. Based on these results, Sechi et al. (2014) performed an Italian multicentre study on the QoL of adult GSD I patients using the standardized questionnaire SF-36 [3]. Thirty-eight patients over 16 years (median age 26.5 years) were included in this study. Their results showed that also adult patients with GSD I may have an impaired QoL. Especially patients with GSD type Ib, women, and those with renal complications were more likely to experience a poorer QoL [3]. Although patients with GSD I had lower median scores in general health perception and social functioning when compared to normative data, they had higher median scores for bodily pain and mental health which might be explained by good coping strategies. QoL data of adolescent and adult GSD I patients are also available from the Swiss hepatic glycogen storage disease registry [13]. This registry includes 27 GSD I patients between 14 and 29 years. QoL was assessed using the SF-12 questionnaire, and in contrast to the above mentioned studies, scores in this sample were within the normal range [13]. Additionally, most patients were well integrated into social and professional life.
Flanagan et al. studied eating attitudes, eating disorder symptoms, and body image among 64 patients with GSD ranging from 7–52 years and found a lower body esteem in children, adolescents and adults with GSD compared to population norms [14]. Interestingly, patients reported growing acceptance of their bodies with age associated with less negative attitudes and behaviours in adulthood.
Our study addressed several aspects of adult life as well as the disease burden perceived by the patients. Different from the above-mentioned studies, we used a self-developed questionnaire that was tailored specifically to the challenges and burdens associated with GSD I, including aspects such as dietary management. Overall, our data demonstrate that most adult GSD I patients live an independent adult life. Concerning education and work, all but 3 unemployed patients (9%) either attended school or university or had a regular working life. Very similar findings were reported by Sechi et al. with an unemployment rate of 11.4% in 38 adult GSD I patients [3]. Data from the Swiss GSD registry comparably showed that most patients were employed or in vocational training with no need of supporting services [13].
In our study, we did not ask for the reason for unemployment, but it is of note that in the European Study on GSD I (ESGSD I) with more than 200 GSD I patients, 11 % were reported to need a special education or work, while 6 % were unable to have a profession because of mental disability [15]. However, it is important to bear in mind that this study includes patients from the “pre-cornstarch aera”, and it is well-conceivable that poorer metabolic control and also possibly later diagnosis might have contributed to a poorer neurologic outcome.
Most patients lived an independent life, while about 32% still lived with their parents (median age of patients living with their parents was 22 years). In this respect, GSD I patients do not seem to differ significantly from the normal population, as German demographic data show that more than 28% of 25-year-olds still live with their parents [16]. About one quarter reported that parents were still mainly responsible for the preparation of meals and dietary management. Difficulty in becoming independent from parents has been observed in patients with inherited metabolic diseases in general [3, 17]. This is well understandable considering the high level of parental involvement in disease management during infancy and childhood [3, 17]. It is also of note, that almost half of the patients in our study preferred to be accompanied to visits in the metabolic outpatient clinic. Supporting patients’ personal responsibility should be one major aim in the transition process from adolescence to adulthood. This includes the early involvement of the patient in the treatment and disease monitoring together with age-appropriate communication and information by doctors during outpatient visits. Providing appropriate information empowers the individual, giving them confidence to manage their disorder in the future [17]. Several patients in our study stated that results of outpatient visits such as laboratory values and necessary therapeutic adaptions were often not well communicated to them.
Living with a chronic disease might not only impact QoL due to the disorder itself, but also due to the necessary treatment, which may be a major challenge. For patients with GSD I this includes frequent meals, strict planning of activities, loss of spontaneity as well as sleep disturbances due to night-time interruptions for nocturnal corn starch intake [14, 18]. When asked for their opinion about the severity of GSD I, most patients ranked GSD I as a disease with moderate severity and disease burden, but rated the challenges of dietary treatment as rather high. The three negative emotions that more than 60% of patients felt with respect to their disease at least sometimes were anxiety, fear, and rage.
Among the aspects addressed in this study, the highest impact of GSD I was perceived on physical performance and fitness. More than 85% of patients either considered their physical fitness moderately or highly impaired. Additionally, some patients expressed at least some degree of uncertainty with respect to the risk of hypoglycaemia during sports. The impact of GSD I on partnership was rated low (53.6%) or moderate (35.7%) by most patients. Interestingly, Sechi et al. reported a lower percentage of married patients with children in their sample of 38 Italian patients when compared to the age- and gender-matched Italian population and suggested that GSD I patients may have more difficulty in forming adult relationships and starting a family than healthy peers [3]. Impact on free time activities and friendships was also considered low by the majority of the study patients. More than 30% of patients reported a high or very high financial impact due to their chronic disease. Studying families with a child affected by a urea cycle defect, Cederbaum et al. reported financial stress as one of the greatest sources of stress in their study cohort [19]. Financial stress affects a significant proportion of patients diagnosed with a chronic illness. In addition to costs for medication that are not all covered by insurance companies, a chronic disease may have an impact on education and professional choices, but also on the fitness for work, thereby affecting the economic status.
Overall, most patients in our study had a rather positive attitude towards their disease and felt able to live a normal life if certain measures are taken. Given the challenges and restrictions associated with GSD I this may reflect good coping strategies in most of the patients. Comparable to healthy subjects, successful coping enables individuals with a chronic illness to emphasize the positive aspects of their lives, thereby reducing general distress [20, 21]. Coping strategies are highly variable, and the perceived disease burden of an individual patient does not automatically correlate with disease severity. This is reflected by the fact that we did not observe significant differences in the perceived disease burden between patients with GSD Ia and GSD Ib, although GSD Ib in adulthood is usually associated with additional problems such as inflammatory bowel disease and other complications linked to neutropenia. Sechi et al. reported that the personal evaluation of “general health” given by GSD I patients was similar to that perceived by patients affected by type 1 diabetes, another chronic disease requiring strict adherence to insulin therapy and the significant risk of metabolic decompensations [3, 22].
Most patients communicated their disorder openly to family members, partners, friends, sporting comrades, teachers and colleagues. In view of the fact that GSD I can lead to life-threatening hypoglycaemia and that in these situations, patients may depend on external help, information of the patients’ social environment and competency to react properly can be lifesaving. In fact, about 20% of patients at least had one severe hypoglycaemia within the last six months during which they required external help.
One might object that our study lacks normative data from healthy subjects and the sample possibly has selection bias only including individuals successfully coping with their condition. However, results clearly vary in all items and clearly demonstrate that participants are neither perfectly compliant nor a selection of relatively mild forms. Our aim was not to do a normative comparison with healthy adults, but to explore how disease-specific facets of GSD type I interfere with adult normative life-events and developmental tasks [23]. We see the significant strength of our study, that instead of using a standardised generic questionaire, describes the QoL of adults with GSD I in a way unfolding how they struggle and cope with their condition and how they live (day and night), thereby providing essential information for all disciplines of the treatment team.