Date on Master's Thesis/Doctoral Dissertation


Document Type

Master's Thesis

Degree Name



Bioinformatics and Biostatistics

Committee Chair

Goldsmith, Linda Jane


Placebos (Medicine); Backache--Psychological aspects


This study investigates the placebo effect in randomized controlled trials of low back pain. This effect has not been analyzed over time or in respect to low back pain. A meta-analysis was performed using the Pubmed/Medline database for low back pain RCTs with a placebo group. It was shown that in studies using the visual analogue scale (VAS) and the numeric rating scale (NRS-11) that there is a positive placebo effect. While the VAS mean change appears consistent up to 6 months, the limited number of studies available (30, n=1150), did not allow certain time periods to be investigated. For NRS-11 (11, n=477), a general change was calculated based on the first measurement taken. It was established that the expected VAS difference in means was -15.6 (-20.9, -10.2) with a p-value < 0.001 and the NRS-11 difference in means to be -1.5 (-2.3, -0.8) with a p-value of < 0.001.