Objectives: We analyzed the content and characteristics of influential health blogs and bloggers to provide a more thorough understanding of the health blogosphere than was previously available.
Methods: We identified, through a purposive-snowball approach, 951 health blogs in 2007 and 2008. All blogs were US focused and updated regularly. We described their features, topics, perspectives, and blogger demographics.
Results: Approximately half of the bloggers in our sample were employed in the health field. A majority were female, aged in their 30s, and highly educated. Two thirds posted at least weekly; one quarter accepted advertisements. Most blogs were established after 2004. They typically focused on bloggers' experiences with 1 disease or condition or on the personal experiences of health professionals. Half were written from a professional perspective, one third from a patient-consumer perspective, and a few from the perspective of an unpaid caregiver.
Conclusions: Data collected from health blogs could be aggregated for large-scale empirical investigations. Future research should assess the quality of the information posted and identify what blog features and elements best reflect adherence to prevailing norms of conduct.