Grounded in more than 30 years of objective, peer-reviewed research by Drs. John and David Wennberg and their colleagues, Health Dialog Analytic Solutions (HDAS) provides insights that help reduce unwarranted variation in healthcare. Unwarranted variation can be defined as differences in healthcare service delivery that cannot be explained by illness, medical need, or dictates of evidence-based medicine, and can be classified into one of three categories:

• Effective care and patient safety, which includes services of proven clinical effectiveness, such as using lipid lowering agents in patients with coronary artery disease.
• Preference-sensitive care, treatment for conditions that have significant trade-offs in terms of risks and benefits for the patient.  But the choice of care is, or should be, driven by the patient’s own preferences.
• Supply-sensitive care, care which is strongly correlated with healthcare system resource capacity and is generally provided in the absence of medical evidence and clinical theory.