Purpose: The Cow's Milk-related Symptom Score (CoMiSS™) was developed as an awareness tool for evaluating cow's milk-related symptoms in otherwise healthy children. Using a convenience sample of participants, this cross-sectional study aimed to determine CoMiSS™ values of symptomatic infants based on retrospectively or prospectively obtained information. Methods: CoMiSS™ values were determined in infants aged <12 months with symptoms suggestive of cow's milk protein allergy or functional gastrointestinal disorders. The exclusion criteria were previous diagnosis with acute or chronic disease, treatment with a therapeutic formula, and in case of breastfeeding, an elimination diet followed by the mother. Two CoMiSS™ values were assessed. A retrospective collection was defined as the collection of data after initial contact with the medical center but before the first medical consultation. A prospective collection was defined as the collection of data within 24 hours from the time of medical consultation but before starting any therapeutic intervention. The CoMiSS™ total and individual component scores obtained retrospectively or prospectively were compared between groups using the Wilcoxon signed-rank test. Results: This study was performed between August and November 2019. Data of 110 children (62 males and 48 females), with a mean±standard deviation age of 18.2±11.7 weeks, were obtained. The total CoMiSS™ value (p<0.001) and some individual component scores (crying, regurgitation, and stool) were significantly lower when collected prospectively than when collected retrospectively. Conclusion CoMiSS™ values were retrospectively and prospectively determined. Lower CoMiSS™ values were obtained during prospective evaluation. Possible differences should be considered when using CoMiSS™ in clinical practice.

Purpose: The Cow's Milk-related Symptom Score (CoMiSS™) was developed as an awareness tool for evaluating cow's milk-related symptoms in otherwise healthy children. Using a convenience sample of participants, this cross-sectional study aimed to determine CoMiSS™ values of symptomatic infants based on retrospectively or prospectively obtained information. Methods: CoMiSS™ values were determined in infants aged <12 months with symptoms suggestive of cow's milk protein allergy or functional gastrointestinal disorders. The exclusion criteria were previous diagnosis with acute or chronic disease, treatment with a therapeutic formula, and in case of breastfeeding, an elimination diet followed by the mother. Two CoMiSS™ values were assessed. A retrospective collection was defined as the collection of data after initial contact with the medical center but before the first medical consultation. A prospective collection was defined as the collection of data within 24 hours from the time of medical consultation but before starting any therapeutic intervention. The CoMiSS™ total and individual component scores obtained retrospectively or prospectively were compared between groups using the Wilcoxon signed-rank test. Results: This study was performed between August and November 2019. Data of 110 children (62 males and 48 females), with a mean±standard deviation age of 18.2±11.7 weeks, were obtained. The total CoMiSS™ value (p<0.001) and some individual component scores (crying, regurgitation, and stool) were significantly lower when collected prospectively than when collected retrospectively. Conclusion CoMiSS™ values were retrospectively and prospectively determined. Lower CoMiSS™ values were obtained during prospective evaluation. Possible differences should be considered when using CoMiSS™ in clinical practice.