Category Archives: Meta-analysis

Ouch! Whose Pain Feels Worse?

levels-of-evidenceIs pain experience as diverse as our populations?  This week I came across an interesting meta-analysis.

A meta-analysis (MA) is one of the strongest types of evidence there is. Some place it at the top; others, 2nd after evidence-based clinical practice guidelines.  (For more on strength of  evidence, click here.)

MA is not merely a review of literature, but is a statistical integration of studies on the same topic.  MA that is based on integration of randomized controlled trials experiment(RCTs) or experimental studies is the strongest type of MA.  MA based on descriptive or non-experimental studies is  a little less strong, because it just describes things as they seem to be; & it cannot show that one thing causes another.

MA example: This brand, new MA included 41  peer-reviewed, English-language, experimental studies with humans:  Kim HJ, Yang GS, Greenspan JD, Downton KD, Griffith KA, Renn CL, Johantgen M, Dorsey SG. Racial and ethnic differences in experimental pain sensitivity: Systematic review and meta-analysis. Pain. 2016 Sep 24 [Epub ahead of print] doi: 10.1097/j.pain.0000000000000731. PMID: 27682208.    All 41 studies used experimental pain stimuli such as heat, cold, ischemic, electrical and others and compared differences between racial/ethnic groups.

Pain reliefMain findings?  “AAs [African Americans], Asians, and Hispanics had higher pain sensitivity compared to NHWs [non-Hispanic Whites], particularly lower pain tolerance, higher pain ratings, and greater temporal summation of pain.” (https://www.ncbi.nlm.nih.gov/pubmed/27682208)  (Temporal summation is the increase in subjective pain ratings as a pain stimulus is repeated again and again.)

Critical thinking:  Given that this is a well-done meta-analysis and that the pain was created by researchers in each study, how should this changequestion your practice?  Or should it?   How can you use the findings with your patients?  Should each patient be treated as a completely unique individual? Or what are the pros & cons of using this MA to give us a starting point with groups of patients?  [To dialogue about this, comment below.]

For more info? Request the full Kim et al. article via interlibrary loan from your med center or school Heart Bookslibrary using reference above.   It is available electronically pre-publication.   Also check out my blog on strength of different types of evidence.

Happy evidence hunting. -Dr.H