A comprehensive evaluation of symptom scores designed to inform the triage and diagnosis of cow’s milk protein allergy in children: a systematic review of the research evidence

Background: Cow’s milk protein allergy (CMPA) is an immune-mediated allergic response to proteins in milk, a common infant food allergy. The wide range and frequency of CMPA symptoms make diagnosis a challenge, particularly in primary care. Symptom scores may improve a clinician’s awareness of symptoms, thus indicating a need for further testing. This systematic review examined the development and evaluation of such symptom scores for use in infants. Methods: Four databases were searched from inception to 3 December 2019, for diagnostic accuracy studies, randomised controlled trials, observational studies, economic evaluations, qualitative studies, and studies reporting on the development of the tools. Experts were consulted for additional studies. Data were not suitable for meta-analysis due to heterogeneity, so were narratively synthesised. Results: We found two symptom scores evaluated in one and fourteen studies, respectively. Estimated sensitivity and specificity ranged from 37-98% and 38-93%. The evaluations of each tool were at high risk of bias or failed to address issues such as clinical and cost-effectiveness. Conclusions: Estimates of accuracy of symptom scores for CMPA offered so far should be interpreted cautiously. Rigorous research based on well-defined roles for the tools and free of potential conflicts of interest is urgently required.