Life · 1 author, 1 centre
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This study compared the OSDI and SANDE questionnaires in 1033 patients and found that their scores cannot be used interchangeably, especially in patients with dry eye disease (DES). Score normalization did not improve agreement, and the SANDE showed limited sensitivity and specificity for classifying DES compared to OSDI. These findings highlight the need for better psychometric validation of dry eye symptom questionnaires.
**Background:** Dry eye disease (DED) is a common, multifactorial ocular surface condition that significantly impacts quality of life. The Ocular Surface Disease Index (OSDI) and Symptom Assessment in Dry Eye (SANDE) questionnaires are widely used to assess dry eye symptoms (DES). However, few studies have compared these tools in a large sample including both patients with and without DES. This study aimed to compare OSDI and SANDE scores in a large cohort and evaluate whether SANDE can differentiate between patients with and without DES.
**Methods:** A total of 1033 patients (mean age 52.6 ± 14.8 years, 60.8% female) from 12 primary eye care centers in Spain completed both the OSDI (12-item Likert scale, score 0–100) and SANDE (two 100-mm VAS questions, final score = square root of frequency × severity) questionnaires during a single visit. Patients with conditions affecting tear secretion, recent eye medication use, active anterior eye inflammation, contact lens use in the last 3 months, or ocular surgery/trauma in the last 6 months were excluded. Scores were analyzed with and without normalization (algebraic norm of a vector). Statistical analyses included Spearman correlation, paired Wilcoxon signed-rank tests, Bland-Altman plots with limits of agreement (LoA), and receiver operating characteristic (ROC) curves. Patients were classified as non-DES or DES using OSDI cutoff values of 12 and 22.
**Key Results:** Of the 1033 patients, 742 (71.8%) were classified as non-DES (OSDI ≤ 12) and 291 (28.2%) as DES (OSDI > 13). Using the OSDI cutoff of 22, 873 (84.5%) were non-DES and 160 (15.4%) were DES. Without normalization, OSDI and SANDE scores differed significantly in the overall sample (mean OSDI 10.74 ± 12.84 vs. SANDE 13.59 ± 21.06, p = 0.016) and in DES patients (p < 0.001), but not in non-DES patients (p > 0.684). After normalization, the overall sample showed no significant difference (p = 0.063), but DES patients still differed significantly (p ≤ 0.001). Spearman correlation between OSDI and SANDE was significant overall (R = 0.53, p < 0.001) but weak in moderate/severe DES (OSDI > 23, R = 0.12, p = 0.126). Bland-Altman analysis revealed a bias (mean difference) ranging from −7.67 (DES with OSDI > 23) to −1.33 (non-DES with OSDI ≤ 12) for non-normalized scores, and from −9.21 to −0.85 for normalized scores. All differences showed significant proportional bias (R² > 0.31, p < 0.001). SANDE scores differed significantly across OSDI severity groups (p < 0.001), but pairwise comparison showed no significant difference between moderate and severe DES (p = 0.656). ROC analysis showed an area under the curve (AUC) of 0.836 (95% CI 0.807–0.866) for OSDI cutoff 12 and 0.880 (95% CI 0.851–0.908) for cutoff 22, indicating limited sensitivity and specificity for SANDE in classifying DES.
**Clinical Implications:** The OSDI and SANDE questionnaires cannot be used interchangeably for assessing dry eye symptoms, particularly in patients with DES. Score normalization does not substantially improve agreement. The SANDE questionnaire shows limited diagnostic accuracy for classifying DES compared to OSDI. These findings underscore the need for improved psychometric validation of DES questionnaires and standardized symptom assessment methods in clinical practice and research.