How physicians allocate causation: a scenario study with factorial design

Causation is a complex concept but important in suspected work-related disease. Physicians routinely make initial assessments of causation as part of their work, but the factors contributing to these assessments are not well understood.

To determine which factors influence a family physician's assessment of causation when seeing patients with suspected work-related injury or illness.

Four groups of family physicians with differing levels of prior reporting (zero, low, medium, high) to the Workers Compensation Board received a questionnaire including four randomly allocated case scenarios. For each scenario there were four versions with either strong or weak causal features suggesting work or non-work factors were important causes or contributors. Responses to questions were made on a series of visual analogue scales.

The nature of the condition and scenario type (i.e. strength of the causal information about workplace and non-workplace factors) were associated with the physicians' opinion on work-relatedness. Understanding the nature of the patient's work, the timing of symptoms and the patients' opinion about work-relatedness were viewed by the physicians as important. A decision that a condition was not work related was influenced primarily by the strength of potential causes outside work. Prior reporting history of the physician was not associated with opinions on work-relatedness, nor the factors considered in reaching this decision.

The characteristics of the case scenario were more important in determining a physician's opinion about work-relatedness than the characteristics of the physician.