Background and Aims Common variable immunodeficiency (CVID) can affect quality of life (QoL) which can be better assessed with validated scales. Our goal was to validate the Turkish version of the Italian CVID-QoL questionnaire. Methods International recommendations for cultural adaptation and translation process of original scale was followed. CVID patients completed Turkish CVID-QoL questionnaire between October 2019 and January 2020. The Short Form Health Survey (SF-36) was used as a comparative questionnaire. Reliability, reproducibility, factor analysis, content validity, convergent validity and discriminant validity were analysed. Results 50 CVID patients were included in the study. 64 % of patients (n=32), the mean age of the patients was 36.68 ± 13.2 years, the median duration of disease was 52.5 months. The instrument had good internal consistency in 50 patients [Cronbach’s alpha: 0.92, emotional functioning (EF): 0.91, relational functioning (RF): 0.77]. It also revealed high reproducibility in 26 patients QoL global, intraclass correlation coefficient (ICC)= 0.80 (95 % CI 0.56 - 0.91); EF, ICC = 0.78 (95 % CI 0.51- 0.90); RF, ICC = 0.82 (95 % CI 0.59-0.92); Gastrointestinal and skin symptoms (GSS), ICC = 0.89 (95 % CI 0.76-0.95); (p <0.001, p <0.001, p <0.001, p <0.001). QoL global, EF and RF scores showed good convergent validity with similar subscales of SF-36. The number of infections within last 3 months had a significant impact on QoL global, EF and RF (p=0.038, p=0.045, p=0.028). Conclusions The Turkish version of CVID QoL scale has appropriate validity and reliability among Turkish patients with CVID.

Backgrounds: Heterogeneous clinical features of antibody deficiency (AD) may cause diagnostic delays. Calculated globulin (CG) (total protein minus albumin) has been proposed as a screening test to prevent morbidity due to diagnostic delays in AD. Our aim is to validate CG as a screening test in AD in Turkish adult patients by comparing its role with gamma globulin analysis in protein electrophoresis. Methods: Fifty serum samples were randomly collected for each level of CG from 1.5 to 2.5 mg/dl and tested for serum IgG, IgA, IgM levels and protein electrophoresis. Cut-off values predicting low IgG levels were calculated for electrophoretically determined gamma globulin and CG. Additionally, the data of 47 patients followed up in our clinic with a diagnosis of primary antibody deficiency (PAD) were retrospectively analyzed. Results: A total of 550 adult patients were included in the study. The CG value predicting patients with IgG <600 mg/dl as a screening test was determined as <2.0 with 83.8% sensitivity and 74.9% specificity. The gamma globulin value which predicted patients with the same IgG value of 89.0% sensitivity and 89.4% specificity was determined as <0.7. In the retrospective analysis, 37 of 47 patients (78.7%) with PAD had a CG value of <2.0 at the time of the diagnosis and all 13 patients (%100) whose gamma globulin values were measured at the time of the diagnosis had a gamma globulin value of <0.7. Conclusion: The determined CG cut-off value of <2.0 can be used as a screening test in Turkish adult patients.