Researchers in Israel set out to see whether medical clowns reduced the distress among pediatric patients during venipuncture.

Fifty-three children ranging in age from 4-15 years were randomly assigned to a study group (with medical-clown intervention) and a control group (no intervention). During their venipuncture procedures, their level of anxiety was measured using two different subjective methods. Children 4- to 7-years old rated their own level of pain and distress by pointing to one of six pictures of faces presented to them depicting increasingly distressed expressions and told to identify the face that represents the pain they experienced. Children seven years and older were asked to mark the point on a line that represented the level of pain during the procedure. One end of the line was labeled as "no pain" while the other end was labeled "worst possible pain." 

To provide an objective assessment, cortisol levels were drawn on each patient since cortisol concentrations quickly increase in the blood under stressful conditions. To control cortisol's daily fluctuation (diurnal variation), patients were drawn only during the evening.

After assessing all patients and testing all cortisols, the authors found a significant difference between the two groups in regards to the objective assessment, but no difference in the objective cortisol levels. Pain scores for all ages without the clown intervention was 7.5 while that of the group exposed to clown intervention was 2.2. The authors concluded medical clowns reduced the distress from venipuncture in children, but not cortisol's response to stress.