LETTER TO THE EDITOR

Response to Professor Hagmar's letter

A. SahlstroÈ mDepartment of Orthopaedics, MalmoÈ University Hospital, MalmoÈ, Sweden

Accepted 16 September 1998

Dear Sir,Thank you for the opportunity to comment on theletter from Professor Hagmar. He and some othersare disturbed by the fact that we failed to prove aconnection between this special type of dynamicweightbearing and knee osteoarthrosis.

The `sitters' were 197 all together. This variablewas included in the interview because it has beensuggested that sitting could cause or possibly evenprevent knee osteoarthrosis. The suggestion of Pro-fessor Hagmar to change the analysis after the fact isof cause questionable. Nevertheless, these analyseswere performed excluding completely the 197 `sitters'.

The weightbearing kneebending OR for knee ar-throsis then was 1.04 (95% CI: 0.65±1.67), p� 0.879.

It is not very useful to make a point of side pro-ducts of a statistical analysis. The possible protectivee�ects of sitting work positions should be studied in aseparate analysis including new data.

Address for correspondence: Dr A. SahlstroÈ m, Departmentof Orthopaedics, MalmoÈ University Hospital, S-205 02

MalmoÈ , SwedenPhone:+46 40 33 10 00; Fax:+46 33 62 00

European Journal of Epidemiology 15: 199, 1999.Ó 1999 Kluwer Academic Publishers. Printed in the Netherlands.