Quality of life in keratoconus: evaluation with Keratoconus Outcomes Research Questionnaire (KORQ)

Abstract

To assess the quality of life of keratoconus patients using the Keratoconus Outcomes Research Questionnaire (KORQ), translated and validated in Portuguese language. The KORQ is the only validated keratoconus specific questionnaire and has a high rating for its psychometric properties. This cross-sectional study enrolled 100 keratoconus patients from a tertiary referral eye hospital between April 2018 and June 2019. Associations between age, sex, allergic conjunctivitis, keratoconus stage, best-corrected visual acuity (BCVA), maximum simulated keratometry (Kmax), steep keratometry (K2), pachymetry, treatments performed, hydrops, and KORQ scores were evaluated using univariate (Wilcoxon test and the Kruskal Wallis test) and multivariate linear regression with stepwise backward modeling. Lower KORQ scores are associated with better quality of life, whereas, higher scores are associated with greater impairment of functional activities and symptoms. Among the 100 patients, mild, moderate, and severe keratoconus were observed in 15%, 46% and 39% of participants, respectively. Univariate analysis showed lower function scores values, with male sex (p < 0.05) and both functional and symptom scores were significantly associated with BCVA < 0.3 (LogMAR) (p < 0.05). Multivariate analysis indicated significantly lower functional scores in individuals with BCVA < 0.3 (LogMAR) (p < 0.001) and those with a history of crosslinking treatment (p = 0.022), while symptom scores were only significantly associated with only BCVA < 0.3 (LogMAR) (p < 0.001). In patients with keratoconus, BCVA in the better eye and history of crosslinkig were factors associated with better quality of life scores using the KORQ.

Factors affecting quality of life in keratoconus

“…More importantly, our results add to the psychometric validation of the questionnaire. 20,21 Our results support the use of KORQ in ophthalmic clinics to capture the impact of keratoconus on activity limitations and symptoms from the patients' perspective and can be used within different cultural contexts and in international comparisons of keratoconus. The use of Rasch analysis to validate the KORQ enabled the generation of linear interval measures of activity limitations and symptoms, and this legitimises their use in parametric tests.…”

“…This is an important finding given that the KORQ was originally developed in an Australian keratoconus population, and the present study shows that the content is equally applicable to an Indian cohort, thereby implying universality of the activity limitations and symptoms faced by patients with keratoconus in the developing, and developed, countries. More importantly, our results add to the psychometric validation of the questionnaire 20,21 . Our results support the use of KORQ in ophthalmic clinics to capture the impact of keratoconus on activity limitations and symptoms from the patients' perspective and can be used within different cultural contexts and in international comparisons of keratoconus.…”

“…We found weakly significant associations between activity limitations and VA in the better‐ and worse‐seeing eye. However, based on clinical knowledge and a previous report by Pinto et al, who also used KORQ, one would expect a stronger relationship between VA and activity limitations 21 . We speculate a couple of reasons for this variation.…”

“…However, based on clinical knowledge and a previous report by Pinto et al, who also used KORQ, one would expect a stronger relationship between VA and activity limitations. 21 We speculate a couple of reasons for this variation. Firstly, the floor effect in our VA data could have accounted for this (59% of our participants had VA of 0.0 logMAR in the better-seeing eye).…”

“…Recently, a vision-related QoL questionnaire specific for keratoconus was described: the Keratoconus Outcomes Research Questionnaire (KORQ), a disease-specific, psychometrically robust, intervalscaling instrument to assess the impact of keratoconus on activity limitations (visual functioning) and symptoms in an Australian population. 19,20 It was further validated using Rasch analysis in Brazilian 21 and Danish keratoconus populations. 22 While there has been an increase in studies investigating the relationship between keratoconus and QoL, research about factors of significance for the QoL in patients with keratoconus is still sparse.…”