Introduction
Common variable immunodeficiency (CVID) is the most frequent and commonly diagnosed symptomatic primary immune deficiency disorder in adults 1 with prevalence ranging from 1 in 10 000 to 1 in 50 000 in different populations 2. CVID is characterized by various clinical conditions such as severe infections, malignancy, granulomatous and autoimmune disorders 1. Although some patients have symptoms from early childhood, the distinguishing feature of CVID is primary hypogammaglobulinemia caused by late onset antibody failure 3. Immunoglobulin (Ig) replacement is the main treatment for the prevention of recurrent infections, and it can decrease frequency of bacterial infections however, it is less effective on other CVID associated complications4, 5.
Patient-focused assessment methods have become more important in the follow-up of the patients with chronic diseases 6. In addition, this approach strengthens the relationship between the doctor and the patient, makes some problems visible that are not noticed routinely and enables better follow-up of diseases and treatments7. In very few studies analysing the psychosocial aspects of CVID, patients are not homogenous group as shown for other chronic diseases 8. In addition, there is a lack of knowledge about one of the rare diseases CVID which has different psychological and social effects both in society, individuals and healthcare providers 9. In recent years, with considerable progress in early diagnosis, increased awareness and Ig replacement therapy led to a significantly extended life expectancy for patients with primary antibody deficiencies10.
Ever since the World Health Organization defined health not only as the absence of disease and illness, but also as the presence of physical, mental and social well-being, questions of quality of life have become increasingly important in health practice and research11. In healthcare, QoL is an assessment of how different aspects of an individual’s life can be affected by a disease or a disability 12. It is a comprehensive concept that is important to evaluate the impact of disease, treatment and symptoms13. QoL is an important health outcome representing the ultimate goal of all health interventions and the use of valid and reliable measurements is essential for providing evidence-based health care 14.
Clinicians mostly deal with more objective data of their patients and whether their illness is cured. QoL scales are mostly used for research purposes and are very rare examples in routine clinical practice. There are many different quality of life scales that contain questions about different aspects of life (environment, social, economics, etc…) that can be used with patients and healthy populations 14. The tools for measuring QoL can be divided into 2 groups: generic and specific. Generic scales can be applied to all kinds of patients and healthy groups including general questions that are not specific to the disease. Specific scales focus on a group or single illness or symptom15. Because generic QoL scales may not capture the positive and negative effects of some specific limitations and effects of each disease and each disease may have specific clinical features and mental effects, it is more appropriate to use validated disease-specific scales.
The measurement of health-related quality of life (HRQoL) in primary immunodeficiency has arisen relatively recently from an effort to document the outcome of therapeutic intervention and the need to obtain information about patients’ well-being as well as objective findings visible to physicians 16. On the other hand, CVID manifestations which are the findings of more common diseases and have been frequently investigated but the knowledge about the effects of Ig replacement therapy on patients is insufficient. Thus, development and validation of a disease-specific HR-QoL survey tool and researchers’ understanding of the quality of life of CVID patients is necessary.
In previous studies, generic health status QoL scales were used such as Short form (SF-36, SF-12) and General Health Questionnaire (GHQ-12) in adult CVID population 16-18. The need for a specific QoL scale that includes better questions has arisen because it can provide the features of CVID more accurately. Quinti et al developed the CVID specific QoL questionnaire in 2015 10 and it was used in scientific studies in Norway and Italy 19, 20.
The aim of this study was to translate this Italian CVID QoL scale to Turkish and investigate the validity and usefulness of CVID QoL questionnaire and determine the impact of CVID on quality of life for use with adult CVID patients by healthcare professionals and researchers.