Surveillance case definitions and clinical diagnoses

Can my patient have hemolytic uremic syndrome even though the specific Canadian Paediatric Surveillance Program (CPSP) case definition criteria are not all present?

To answer this question, one must remember that the surveillance case definitions used in the CPSP establish uniform criteria to be used by each participating paediatrician for reporting a disease or condition. Uniform criteria ensure the usefulness of surveillance data for analysis and interpretation, which, in turn, affects policy change and public health action. CPSP surveillance case definitions may differ in their use of clinical, laboratory and epidemiological criteria to define cases. For example, the case definition for diarrhea-associated hemolytic uremic syndrome requires both clinical (a prodrome of enteric symptoms) and laboratory data (evidence of acute renal impairment with elevated serum creatinine levels, microangiopathic hemolytic anemia and thrombocytopenia). In contrast, the definition for a confirmed case of Smith-Lemli-Opitz syndrome only requires laboratory data. Surveillance case definitions should not be used as the sole criteria for establishing clinical diagnoses or for determining the standard of care necessary for a particular patient. Clinical signs and symptoms can manifest themselves progressively during an illness; accordingly, the use of additional clinical, epidemiological and laboratory data may enable a physician to diagnose a disease, even though the formal surveillance case definition may not be met. Failure to meet the surveillance criteria of the formal case definition should never impede or override clinical judgment during the diagnosis, management or treatment of patients. In situations in which all of the criteria are not met, treating physicians are encouraged to report the cases, and the principal investigator will decide whether it should be included in the final data analysis.