How Google and Apple may help with one of chronic pain's more vexing questions

At the recent Apple iOS8 announcement, a new software tool referred to as ‘HealthKit’ was revealed, that is intended to be a central hub for consolidating all of your health-related data.  This appears to include not just your history of illness or disease, but also your health-promoting behaviours such as activity, sleep, and diet.  Not surprisingly, Google appears to be preparing its own health-information consolidation service, which from all appearances will do largely the same thing.  These services make sense on many levels, especially considering the explosion in health- and activity-tracking devices known largely as ‘wearables’, leading us closer to the notion of a quantified self.  In fact, my Samsung smartphone gives me a tally of the steps I’ve taken every day by virtue of using the embedded accelerometer in the phone, just for carrying it around with me.  It’s by no means a completely accurate picture of my daily activity, it doesn’t discriminate walking from running or climbing for example, and the toll on battery life means I often leave my office with the phone sitting on the charger.  However, assuming my behaviour in this regard is reasonably consistent, that is, assuming I tend to leave my phone on the charger for quick trips around the building but take it with me when I leave for any extended period of time, these types of activity trackers (whether built into your phone or a stand-alone wearable) should be able to identify significant changes in my behaviour over an extended period of time.

So how does this address the vexing problem in the title?  The problem I’m referring to is the influence of pre- and post-traumatic physical activity status on the subsequent onset and/or maintenance of chronic pain or disability.  Our systematic reviews would indicate that pre-accident activity doesn’t appear to have much of an effect on post-trauma trajectory in whiplash, and the balance of evidence is equally ambiguous in other conditions.  We have yet to see compelling and consistent evidence that inactivity following injury in fact plays an important role in the development of chronic problems, as the ‘vicious cycle’ or fear-avoidance models would suggest.  One of the big challenges in conducting this research is that, in all but the largest of population-based cohort studies, most researchers can’t go back in time and collect pre-injury physical activity or sleep data, necessarily relying instead on self-report of study participants.  Recall or desirability bias is of course a huge problem with such approaches, so I would say that we really don’t know the impact of either pre-trauma or post-trauma daily activity on recovery/chronicity.  However, what if we were able to tap into the potential wealth of activity and health data that iOS and Android promise to start collating for us in the near future?  While they may not offer accurate indicators of actual activity yet, there is certainly potential to use these tools to find relative changes in activity from the average 1-year activity pre-injury to the average daily activity post-injury.  Of course, this also opens the possibility of abuse of such systems (perhaps, if I’m trying to prove how much my injury has affected my physical activity, I may leave my phone in my office a bit more often), but until people pick up on that game, there may be a window of opportunity for those of us ready to take advantage of these data that can lend some useful insights into pre-injury health and activity and the subsequent development of post-injury chronicity.  Something to keep an eye on perhaps.