Purpose: The purpose of this study was to elicit and compare clinically meaningful differences from parents and providers in anticipation of completing a randomized trial to determine whether blood-transfusion therapy prevents further neurologic morbidity in children with sickle cell disease and silent cerebral infarcts.
Method: Rankings, ratings, and standard-gamble assessments were elicited from parents and providers across all English-speaking sites of the SIT Study. Utilities were calculated by chaining standard gamble assessments elicited between the “best” and “worst” scenarios and standard gamble assessments of those anchors against Death and Life Without Sickle Cell Disease.
Result: There were 64 parents (13 sites) and 38 providers (6 sites) whose data were interpretable. Parents ranked the outcomes in the following order, from least to most preferred: Paralysis, Viral Infection Following Transfusion, Chest Syndrome, Pain Syndrome, Iron Chelation Following Transfusion, School Problems, Transfusion, and Sickle Cell Disease With No Other Problems. Parents ranked by one rank, on average, Paralysis higher than providers (P .0009), Pain lower (P .005), and School Problems lower (P.004). Parents rated Pain lower by 20 points (out of 100) than providers (P .02), and their chained utilities were 10 points (out of 100) lower than providers (P .02). Numeracy contributed mildly to these differences, but gender and educational attainment did not. The median Maximum Probability of Silent Stroke Willing To Accept To Avoid Transfusion was 10%, compared with the target trial goal of 3% to prevent progression of silent cerebral infarct.
Conclusion: Parents and providers in the SIT Study generally agreed about their preferences of undesirable clinical outcomes, except for pain syndrome, which providers ranked as worse than parents. The target trial goal of 3% progression of silent cerebral infarct while receiving blood transfusion was below parents’ threshold of silent-stroke probability. However, given that these parents had already consented to take a chance on transfusion by joining the study, we might expect a lower threshold in the general sickle-cell population, and therefore some lack of enthusiasm for the technology, even if the study is successful. We are currently collecting 3-year post-study data of both parents and providers to determine how participation in the study affected those preferences; these data will provide a unique data set in clinical-trial methodology and in sickle-cell disease research.
Candidate for the Lee B. Lusted Student Prize Competition