Abou-Raya A, Abou-Raya S, Khadrawe T. Methotrexate in the treatment of symptomatic knee osteoarthritis: randomised placebo-controlled trial. Ann Rheum Dis 2014. Published Online First 27 Mar 2014. This paper has been retracted. Following publication ARD raised concerns with the authors and asked the Faculty of Medicine of the University of Alexandria to investigate. The report of the Investigation Committee included the following findings:

“Great concerns rose about the following points:

1. Aggregation of age data at the age of 60 years constituting 26.4% of the placebo group and 22.2% of the Methotrexate group despite that data is ranging between 60 to 78 years and 60 to 84 years in both groups respectively.

2. Correlation between age of the disease is evident among only the Methotrexate group (r=0.323, P=0.006) while no correlation between both variables in the placebo group (r=0.131, P=0.275).

3. Coding system of the comorbidity variable is not clear – if it is either scale variable or categorical variable – which raises concerns about validity of the method of analysis used.

4. Analysis of comorbidity (using data sent by the authors) revealed different results than that published (page 7 in output attachment).

5. Baseline VAS was nearly perfectly correlated in the placebo group with its 2nd reading at 28 weeks (r=0.927, P<0.0001), while that correlation doesn't not even exist among the Methotrexate group (r=0.023, P=0.859).

6. “VAS mean difference” used in the paper was calculated using the mean percent difference which was not clear or mentioned in the research published.

7. Errors were made in the analysis of “VAS mean difference” by including the missing values (given the code 99) in the analysis resulting in an evident errors (Page 12 output attachment).

8. Analysis of the scores used yielding different results than that published.”

The Investigation Committee's report concluded: “There is an unintentional mistake in the statistical process, with errors in collection of data in some groups”.

In the course of discussions with ARD about the paper, over a number of months, the authors provided three different data sets and proposed corrections to the text and two of the tables in the paper. ARD considered that the corrections to the paper were significant and was not able to agree to them for that reason and because of unresolved concerns about the reliability of the data in the paper and in the corrections. The authors do not agree with ARD's concerns.