Int. J. Environ. Res. Public Health 2009, 6 499 years, and Figure 6 shows an aggregated view of the top treatments tried by the CureTogether endometriosis community. Individual tracking data, medications and other relevant information can be printed from the websites to expedite interaction at in-person doctor visits. Figure 6. CureTogether patient-entered treatment statistics. Self-tracking information is further incorporated into the PatientsLikeMe site by mapping the data to a graphical representation of the patient as shown in Figure 7, a stick figure shaded with different colors per symptom severity and disease stage so anyone looking at the profile can assess the patient’s status immediately. Figure 7 depicts two patients with ALS, one with arms onset (top diagonal line) and one with bulbar onset (bottom diagonal line), tracking their condition progression by year (x-axis, years 0-10) and decline in Functional Rating Scale (FRS) (y-axis, 0-45). The site’s collaborative filtering allows users to find “patients like me,” which is important since similar others are the most relevant for providing and sharing information. Figure 7. PatientsLikeMe peer disease tracking over time with easy-to-read graphical images of patient status. Clinical trials access A fourth type of service offered by some health social networks is information regarding clinical trials. Even the presence of health social networks makes traditional clinical trials more efficient through the availability of large searchable online databases of patients with health history and condition information. Pharmaceutical companies, industry analysts, policy architects and other interested parties can assess demand and market size directly from health social network websites.