Methodological Concerns In The Study Of The Immune System In Schizophrenia

Background. Studies of immune measures in schizophrenia have shown differences with control subjects on a number of measures. However, immune measures are often not detectable in the serum or CSF of human samples and in many studies it is not clear how this was dealt with in the analysis. Methods. CSF IL-6 was measured by ELISA in 61 drug free male schizophrenic (DSM-IIIR) patients and 25 well-screened healthy male control subjects. Serum IL-6 was measured in 43 of the 61 patients, and in 16 control subjects. Data were analyzed with and without non-detectable values to determine if this affected the results. Results. Using a value of "0" for non-detectable values resulted in significant differences between patients and controls in plasma interleukin-6. However, if these values were treated as missing, the difference was not significant. Conclusions. The treatment of non-detectable immune measures has demonstrable effects on the analysis and interpretation of the results.