Awesome followup post and comments.

One thing I find useful when choosing to share PHI (or not) is to break down the issues relevant to me and my value system in a personal decision matrix.

This allows me to shy away from generalizations about 'should' or 'should not' outside my personal sphere of decision-making, and also to have a realistic, reciprocally valuable (I hope) conversation with another person who may be considering sharing PHI.

Here are some of the factors I consider:

1. Safety – does sharing *this specific PHI* jeopardize myself, or my family in any way? (ie can health insurers use this information to deny my coverage?)
2. Security – does sharing this PHI in the format allowable by the social media site/service jeopardize any other information, or my future financial health/wellbeing? (ie do I use the same passwords, etc)
3. Privacy – does sharing *this specific PHI* reveal things I want to be 'openly available' in the public space if it's a public network, or would I rather share them via a closed or anonymized listserve? Would I say them aloud on a mobile phone in a crowded mall? Would I pay to post them on a billboard? (Obviously that last one's a stretch but if I *wouldn't* want to see that info posted on a billboard, why the heck would I consider sharing it in an open fashion on a public social network?)
4. Utility (self, self+doctor, others, self+others, self+others+doctor) – does sharing *this specific PHI* have utility/value for me? ie does it make me feel better to get this off my chest (catharsis, therapy, etc). Does sharing *this specific PHI* have value for my conversations with my doctor? Even peripherally? Does talking about it on a social network make me think about my condition(s), and/or decision-making and priorities in a new way that might influence my conversations with my care providers? Does sharing *this specific PHI* have a potential or inferred value for anyone else? (this may be the hardest to judge since I can attempt to predict what may be useful for someone else but it's a crapshoot at best)
5. Access – to whom does sharing *this specific PHI* on this site or service grant access to my information? Is the network structure opt-in (ie only my friends on Facebook can view this update) or is it publicly available a la Twitter public timeline?
6. Control – who has control over removing, revising, or redistributing my PHI should I choose to share it with this group, at this time, on this network? Does the site's User Agreeement or Terms of Service grant me control, or can they store, aggregate, and anonymize/use/sell my data on the backend?
7. R+R (personal reputation and community 'reliability') – what are my personal motivations for sharing this PHI? Do I want to gain a certain reputation (ie "I am an ePatient") by doing so? Do I hope to increase the group value by adding to the knowledge network?

I tend to give myself 100 points to distribute among the relevant factors.

Where I give points are the factors I use to make the decision to share personal health information (PHI) which changes episode by episode and site by site.

I do not often, for example, share PHI on Facebook, but I share ODLs (observations of daily living relevant for overall wellness) quite often on Twitter.

I also often choose to share PHI and my personal health narrative in the blogosphere (Posterous).

I take all the above factors into account *each time* before I do so, as well as the audience and community/communities with which I'm involved on each site, and their motivations for perusing my content.

This may seem like a complicated exercise, but it's worth talking about. You can drop factors important to you into a simple Google Docs spreadsheet and distribute points from there.

Hope this may be helpful to someone other than myself!