Self-report pain scales valid for most children

By MD Will Boggs

 The Faces Pain Scale-Revised (FPS-R) and Color Analog Scale (CAS), two self-report pain scales commonly used in children, are valid for use in most cases, according to an observational study in children ages four to 17.

"I would advise caution when using the FPS-R and CAS in four-year-olds," Dr. Daniel S. Tsze from Columbia University College of Physicians and Surgeons, New York, told Reuters Health. "I would say that there may still be a role for these scales in identifying pain and changes in pain. However, these scales may not be useful for determining the exact severity of pain, or exact degree of change in pain score, in this age group."

Although commonly used in clinical and research settings, the degree of validity of the FPS-R and CAS for emergency room use has not been well studied.

Dr. Tsze and colleagues analyzed the two tools in 620 young emergency department patients and report their findings September 2nd online in Pediatrics.

Convergent validity, the degree to which two different scales that are supposed to measure the same thing produce similar results, seemed inadequate only among children younger than age seven, and in African American children compared with white children.

Discriminative validity, the degree to which a test is actually measuring only the construct it is meant to measure (here, pain) and not something else (e.g., anxiety), was evident as both FPS-R and CAS scores were significantly higher in children presenting with painful conditions than in the nonpainful group.

Responsivity was also demonstrated by differences in both FPS-R and CAS pain scores before and after an analgesic was given to children with painful conditions.

Test-retest reliability, assessed in 40 children, was significant, with Pearson correlations of 0.77 for FPS-R and 0.89 for CAS.

The repeatability coefficient, a measure representing the maximum difference expected to occur with a probability of 95%, due to the inherent imprecision of a scale, between repeated measurements in a patient whose pain is expected to remain the same, was +/- 0.53 for FPS-R and +/- 0.35 for CAS, where lower is better.

"Pain scales, whether they are self-report or observational, are useful but imperfect," Dr. Tsze said. "Just as the pain experience is made up of many different components, pain assessment should also be multifactorial and not rely on one pain scale alone."

"Pain assessment should include a child's self-report of pain; observing for behaviors indicative of pain; and interpreting these findings in the context of the clinical situation and determining if they are consistent with any probable sources of pain," Dr. Tsze said.

Coauthor Dr. Carl L. von Baeyer from the University of Saskatchewan in Saskatoon told Reuters Health, "CAS should not be used with four-year-olds - it has never been promoted or supported for use in this age group. Work continues on the FPS-R with this age group - several studies show that many or most four-year-olds can get it, but certainly the proportion who do not get it is greater than in older children."

But, he added, "Green light for FPS-R for five-year-olds and older. The best data suggest that five or six would be the lower limit for CAS."

Dr. Eufemia Jacob from UCLA School of Nursing in Los Angeles, who wasn't involved in the study, told Reuters Health by email, "For older children eight years and older, the Numerical Rating Scale (NRS) and VAS (Visual Analog Scale) are useful both clinically and in research; both were well validated. The use of FPS-R does not offer additional advantage (in relation to the NRS and VAS). Previous literature has documented that FPS-R is the least preferred tool by children and adolescents."

"There is wide variability in understanding of pain in younger children (<5 years)," Dr. Jacob said. "FLACC (Face, Legs, Activity, Cry, Consolability) scale has been validated in younger children and used both clinically and (in) research, and I would use the FLACC for this age group."

Dr. Achim Elfering from Institut fur Psychologie, Bern, Switzerland, who has also studied pain scales in children but wasn't involved in this work, told Reuters Health by email, "FPS-R and CAS should not be avoided. The lower reliability - in my view - is not specific for the instruments but should become a genuine research topic."

"We do not know whether pain is generally more fluctuating in this age group compared to older children - so not unreliability but true change would be recorded in reliability assessments," Dr. Elfering said. "We should do ambulatory assessment studies with many repeated assessments to clarify this."

SOURCE: http://bit.ly/1ebcYC9

Pediatrics 2013.Self-report pain scales valid for most children