Complex Regional Pain Syndrome (CRPS) is a condition which can invoke fear and dread both in patients and healthcare providers. Many patients I’ve met who have been told they’ve got CRPS have done a little searching on Dr Google and come away terrified, thinking CRPS is a life sentence, worrying it might never get any better, having read that sometimes CRPS leads to an amputation. It seems there is a lot of scary information out there.
Our recent research review suggests Dr Google is a bit of a misery-guts who thrives on the drama of worst case scenarios. We systematically reviewed all the previous research which aimed to assess the outcomes of CRPS, and published our review in the Journal of Pain . We wanted to know how many CRPS patients get better, and to what extent do they recover? We included three types of research studies in our review. The first were prospective studies, which recruited a bunch of CRPS patients as soon as they developed CRPS (e.g. soon after they fractured their arm), and then followed those patients up over time to see how many of them got better. The second were studies which were retrospective, for example the researchers might have tried to contact all the CRPS patients who were previously treated in a particular clinic or who were identified on a database, and then found out how well they had recovered. The third type of studies were cross-sectional: studies that recruited CRPS patients and grouped them according to how long they’d had their CRPS, and then measured the types of symptoms that patients in each group had. Obviously the best kind of study for answering our question was the first type: the prospective studies, because they had the greatest chance of capturing all the cases of CRPS. Unfortunately only 3 of these studies existed, so we had to include the other types as well. So keep in in mind that the retrospective studies and, in particular, the cross-sectional studies were often biased because they were less likely to include patients who’d gotten better quickly.
What we found was quite interesting. The prospective studies showed that on average, the outcomes of CRPS were quite good, with less than 20% of the CRPS patients continuing to have pain at about 1 year after their CRPS developed. However, when we looked at the results of the retrospective studies, they were very mixed: some of the studies showed that most patients got better, and some of the studies showed that most patients didn’t. This might be because each study used completely different methods: some just sent patients a questionnaire or looked at the medical records to see how they were getting on, while other studies carefully interviewed and examined patients. When we looked at the cross-sectional studies, we found that these showed that patients with the longest duration of CRPS were most likely to have pain and sensory symptoms, which some readers might think means that CRPS gets worse as time goes by. In reality, it doesn’t: It might be that those who have a lot of sensory symptoms at the outset are less likely to get better but we can’t be certain from the research that’s been done.
Overall, what we interpreted from the review was that amongst people who have early signs and symptoms of CRPS after an event like a fracture, there is a high chance of recovery. However, it was also clear that there are a proportion of people who develop more lasting symptoms, and some of these cases can be severe. We speculated that there might be subtypes of CRPS, something that previous researchers have also suggested, so perhaps not all cases of CRPS are equal [2;3]. In reading this, please bear in mind that the review also found that there were a number of quality issues with the body of literature, and hence any conclusions are tentative. Over the years, CRPS has had many different names, definitions and sets of diagnostic criteria, so some of the studies might have been looking at apples, while others were looking at oranges. Also, it’s really difficult for researchers to recruit a ‘representative’ sample of CRPS patients and some of the studies had samples that you might expect to do well (for example people who had previously responded well to treatment), and others had samples that you might expect to do poorly (e.g. people who were attending a specialist pain clinic). But overall the message from this research is that we don’t really have a crystal ball regarding CRPS: the majority of people probably recover quite well within a year but some people do develop longer-term problems, and as yet we don’t know what the difference is between these two groups. A topic for more research I say!
Debbie Bean is a Health Psychologist at The Auckland Regional Pain Service (TARPS) and is also part-way through completing her PhD at The University of Auckland. She is currently involved in research designed to understand more about recovery from complex regional pain syndrome, the role of psychological factors in pain, and neuroplastic changes associated with pain.
 Bean, D., Johnson, M., & Kydd, R. (2014). The Outcome of Complex Regional Pain Syndrome Type 1: A Systematic Review J Pain DOI: 10.1016/j.jpain.2014.01.500
 Bruehl, S., Harden, R., Galer, B., Saltz, S., Backonja, M., & Stanton-Hicks, M. (2002). Complex regional pain syndrome: are there distinct subtypes and sequential stages of the syndrome? Pain, 95 (1-2), 119-124 DOI: 10.1016/S0304-3959(01)00387-6
 de Mos, M., Huygen, F., van der Hoeven-Borgman, M., Dieleman, J., Ch. Stricker, B., & Sturkenboom, M. (2009). Outcome of the Complex Regional Pain Syndrome Clin J Pain, 25 (7), 590-597 DOI: 10.1097/AJP.0b013e3181a11623