When MobiHealthNews reported on the recent Pew findings last week, we quoted Susannah Fox as saying the Long Tail of the app market likely sustains some niche health apps. One such app, the HysterSisters hysterectomy support app, demonstrates how an existing online community can leverage a social health app with a self-tracking component for additional support.

HysterSisters has been around since 1998 in the form of a website and online community for women facing upcoming hysterectomies or recovering from the surgery. Women create anonymous accounts where they can talk about the practical and emotional challenges associated with getting the surgery. The website also offers information and advice for hysterectomy patients and women going through menopause.

"Women are the best when it comes to support, no matter what they’re going through, and they like telling stories," said HysterSisters founder Kathy Kelley. "Whether they’re having a baby or having surgery, they want to talk to each other."

Kelley started the website as a hobby in 1998. Since then, she said, it's grown from about 100 unique visitors per day to about 30,000. She started monitoring the mobile device traffic to the website about five years ago, and found that for the most part it stayed light. It started to pickup in 2011, and by 2012 40 percent of the site's traffic came from mobile devices.

"I started worrying about those women, especially younger women who maybe only get online through their iPhones," Kelley said. "So I updated the website's mobile skin, but then I started hunting for an app developer. I wanted to give these women some new tools."

The app, which launched for iPhone in August, provides a portal to the existing online community, but it also has new, personalized tools that wouldn't be possible in any other context. When a woman downloads the app, it prompts her for the date of her hysterectomy. From then on it creates a personalized schedule of articles, videos, suggested doctor visits and questions, and other resources tailored to her point in the surgery timeline. It also includes a tracking component, encouraging women to track their symptoms in a log they can later print out and give to their doctor.

Since it's launch, Kelley's seen about 650 downloads of the app per week, mostly from women who already use the website. She hopes the publicity push in the next few weeks (which will also include the launch of an Android version) will see these numbers go up, especially among app-oriented women who aren't already part of the online community.

There's something to be said for entering the app space with an established base of users and a proven formula. Patients facing a major health change, like a surgery, are likely to turn to Google, and increasingly to their smartphones, for information and support. HysterSisters draws users in at the point of their surgery, but many women continue to participate long afterward, mostly because of the social aspect of the site. It will be interesting to see if those factors make the health tracking aspect of the app any more successful than other self-tracking apps.