Jadad scale

The Jadad scale, sometimes known as Jadad scoring or the Oxford quality scoring system, is a procedure to independently assess the methodological quality of a clinical trial. It is named after Colombian physician Alex Jadad who in 1996 described a system for allocating the trial a score of between zero (very poor) and five (rigorous). It is the most widely used such assessment in the world, and as of 2017, its seminal paper has been cited in over 13000 scientific works.

Randomization

Blinding

Withdrawal.

High JADAD score, reflecting better methodological quality 1), was associated with lower chance of demonstrating a benefit from surgery. The JADAD scale places much emphasis on blinding and the inter-rater agreement for the JADAD scale has been questioned 2). Still, almost half of the neurosurgical studies in a review had a JADAD score of 1 or 2, indicating rather poor quality 3).

1)
Jadad AR, Moore RA, Carroll D, Jenkinson C, Reynolds DJ, Gavaghan DJ, McQuay HJ (1996) Assessing the quality of reports of randomized clinical trials: is blinding necessary? Control Clin Trials 17:1–12
2)
Clark HD, Wells GA, Huet C, McAlister FA, Salmi LR, Fergusson D, Laupacis A (1999) Assessing the quality of randomized trials: reliability of the Jadad scale. Control Clin Trials 20:448–452
3)
Solheim O. Randomized controlled trials in surgery and the glass ceiling effect. Acta Neurochir (Wien). 2019 Feb 23. doi: 10.1007/s00701-019-03850-3. [Epub ahead of print] PubMed PMID: 30798480.