Social networks and collateral health effectsBMJ 2004; 329 doi: http://dx.doi.org/10.1136/bmj.329.7459.184 (Published 22 July 2004) Cite this as: BMJ 2004;329:184
- Nicholas A Christakis (email@example.com), professor
- Department of Health Care Policy, Harvard Medical School, 180 Longwood Avenue, Boston, MA 02115
Since a patient or a clinical trial participant is connected to other people through social network ties, medical interventions delivered to a patient, quite apart from their health effects in that person, may have unintended health effects in others to whom he is connected. The cumulative impact of an intervention is therefore the sum of the direct health outcomes in the patient plus the collateral health outcomes in others (figure). These effects, in both the patient and in their social contacts, might be positive or negative. Doctors, trialists, patients, or policy makers might see reason to take them into account when choosing treatment or evaluating benefit.