Key messages

• It is uncertain whether vitamin C prevents complex regional pain syndrome in patients with extremity trauma undergoing surgery because the certainty of the evidence is very low.

What is the evidence.
See evidence matrix  in Epistemonikos later

We found two systematic reviews [1],[2] including four primary studies reported in six references [3],[4],[5],[6],[7],[8], of which only one correspond to a randomized controlled trial (reported in two references) [6],[7].

What types of patients were included

Adults (18 years or more), with a fracture of one or both wrists, under conservative treatment or surgery.

All types of wrist fractures were included.

What types of interventions were included

The study compared daily doses of 200, 500 and 1500 mg for 50 days starting the day of the injury.

What types of outcomes were measured

Incidence of complex regional pain syndrome clinically diagnosed using Veldman criteria, having to fulfill 4 of the 5 following criteria:

• Unexplained diffuse pain, disproportionate to the stage of fracture treatment.
• Difference in skin color relative to the other hand and wrist.
• Diffuse edema
• Difference in skin temperature relative to the other hand and wrist
• Limited active range of motion of the wrist and fingers, disproportionate to the stage of fracture treatment.

To whom this evidence does and does not apply

• This evidence applies to patients 18 years or older with history of wrist fracture that require surgical treatment for its resolution.
• Taking into account physiopathological reasons, it is reasonable to think the intervention effect would be similar in other traumatic events involving the limbs, such as foot and ankle fractures surgically treated. The identified observational studies include some of these populations but the very low certainty of the evidence that comes from them does not modify our conclusions substantially.

• This summary only considers the incidence of complex regional pain syndrome as an outcome.

• Even though there are no adverse effects reported in healthy patients with the use of vitamin C with the doses recommended by the analyzed study, it is not possible to conduct an adequate risk/benefit balance due to the very low certainty of the evidence about the benefits.

• Although it is a low cost intervention, it is not possible to conduct an adequate cost/benefit balance due to the very low certainty of the existing evidence.

Differences between this summary and other sources

• The key messages of our summary are partially discordant with the conclusions of the individual systematic reviews identified [1],[2], which provide a more optimistic conclusion. This is partially explained because they give more weight to the observational studies. However, the inclusion of these studies in our summary does not change our conclusions substantially.
• The main conclusion of this summary is partially discordant with the existing clinical guideline, that incorporates a low proportion of the identified evidence because it did not exist when it was published [9].

• The probability of future evidence changing what we know is very high, because of the very low level of certainty of the evidence.