Background: Criterion-related validity of the Mainz Pain Staging System (MPSS) was examined.
Patients and methods: The effect of staging of pain on pain-related and psychosocial measures was investigated in a cross-sectional design among 478 patients with chronic low back pain in inpatient orthopedic rehabilitation (ICD-10 diagnoses: M45.4/M45.5, M54.4/M54.5). Pain-related measures were selected from the German Pain Questionnaire of the International Association for the Study of Pain (DGSS). The psychosocial measures depression (ADS), anxiety (HADS-D), somatization (SCL-90-R), quality of life (SF-12), functional capacity (FFbH-R), pain sensation (SES) as well as pain experience and strategies of coping with pain (FESV) were assessed. Furthermore, the frequency distribution of scores in the clinical range in pain-related and psychosocial measures depending on the staging of pain was examined. Finally, initial indications of the predictive validity of the MPSS were investigated among 116 inpatients.
Results: Staging of pain had a significant impact both on levels of measures and proportion of clinically referred patients. Patients in stage III, but also those in stage II showed significantly impaired levels. Patients in stage III also showed more scores in the clinical range than expected in the lowest pain intensity, ADS depression, somatization of the SCL, functional capacity, and pain sensation. The MPSS before rehabilitation, together with mental health, seem to be a good predictor of depressive symptoms 6 months after rehabilitation.
Conclusion: The results support criterion validity of the MPSS, however, they also corroborate the concept that identification of medium and high grade pain by the MPSS has to be followed by a psychological diagnostic assessment. By this stepwise diagnostic process, therapy aims and treatment regimens can be designed more adequately.