Serum sepsis, not sickness.

Rarely taught in medical schools, clinical reasoning is the ability to discern the important from the unimportant and to arrive at accurate and efficient clinical conclusions. Identifying errors in reasoning is difficult; however, undetected clinical reasoning errors can have exponential consequences. As quality and patient safety come into focus, identifying and preventing clinical reasoning errors have become imperative. The authors present a case of a man sent for admission from a subspecialty clinic diagnosed with infliximab-induced serum sickness. Not countering the expert's diagnosis, initial workup failed to diagnose joint abscess and sepsis. Heuristics are mental shortcuts used to make decision making more efficient but can lead to error. The anchoring heuristic, premature closure, confirmation bias and the blind obedience heuristic are examples. Introspective surveillance and interactive hypothesis testing defend against heuristics. The authors conclude by discussing 4 types of hypersensitivity reactions, serum sickness in particular, and the chimeric nature of infliximab.