One of the themes identified in the EBM manifesto is that of Evidence Informed Synthesis. EBM methods are relatively new and efforts to strengthen the rigor have focused on improving the transparency and accuracy of measurement. As methodologists we acknowledge the need to keep improving these methods to reduce measurement error and get us ever closer to the best information.
However we are still far from patient centered evidence synthesis. We face a problem similar to that facing clinical practice itself. While the patient wants a whole body approach to their health, we often deliver medical care piecemeal, particularly in the US. Specialists treat diabetes, or hypertension, or dermatitis or gastro-esophageal reflux disease but don’t integrate care decisions leaving the patient to struggle to manage the separate care processes for all of the above.
Like the specialists who treat only the pieces of the patient, our evidence summaries often focus on the science for a singular intervention for a singular disease. Sometimes they may compare several interventions, but the focus is still likely to be on one disease. Rarely do they synthesize the evidence needed by clinician and patient to evaluate how interventions for disease x impact disease y and z, and how the multiple interventions for each individual disease impact them all.
Many patients with conditions serious enough to warrant clinical intervention have multiple conditions. And these patients rightly want to know how to maximize their whole health while living with these conditions. Which interventions will maximize benefits over harm for all their maladies?
The challenge is huge for EBM and its practitioners. Many of the primary trials of interventions are conducted by manufacturers and designed to maximize demonstration of effectiveness in idealized patients with no co-morbidity. Observational studies often provide better estimates of safety and effectiveness in complex real patients. Our methods for evidence synthesis must be as rigorous as possible within these constraints of providing useable information about the interactions between diseases and interventions in complex patients.
We need to move past precise measurement of the pieces to practical assessments of the whole.