• the existence of CRPS until one year after follow-up
  

• difference in outcome and dose (dose comparison) after one year of follow-up
  

The trial was designed as a multicentre, randomized, controlled study. Three hospitals in the Netherlands participated in this study, using the same experimental design. Adults (18 years or above) with a wrist fracture who were seen in the emergency department of each hospital were asked to participate in this study.

Patients were asked to start the trial medication on the day of the fracture. Two capsules had to be taken once daily for 50 days. Patients were allocated randomly to receive either placebo or a dosage of 200, 500 or 1500 mg of vitamin C daily.

The endpoint of the study was defined as the presence of CRPS at any moment, in the period up to one year after the fracture. All participants and physicians were unaware of the treatment allocation. Patients were seen after 1 week, 4 or 5 weeks (or when the cast was removed), 6 or 7 weeks, 12 weeks, and 26 weeks. After one year patients were interviewed by telephone or received an inquiry letter with a postage-paid envelope for their reply. The normal fracture treatment, either conservative or operative, was not compromised by the protocol, and if necessary patients were seen more often and/or at other times than planned.

Complex regional pain syndrome was diagnosed when four of the following five symptoms were present throughout an area larger than the wrist, including the area distal to the wrist (hand and fingers), and if they occurred or increased after activity: unexplained diffuse pain, which is not in normal relation to the fracture; difference in skin color relative to the other arm; diffuse edema; difference in skin temperature relative to the other arm; limited active range of motion, unrelated to the stage of fracture treatment. If CRPS was diagnosed, the end point of the study was reached and the protocol was terminated to enable treatment for CRPS.