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Pain Interference Index (PII)
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Supplemental: Cerebral Palsy (CP)
Short Description of Instrument
The Pain Interference Index (PII) measure is a 6-item self-report questionnaire that assesses pain interference using the past 2 weeks as a recall period. Respondents rate items on a 0-6 scale to indicate how much pain has interfered with various activities, i.e., school, activities, friends, mood, mobility, and sleep (Holmstrom et al., 2015; Martin et al., 2015).
The PII takes about 1-2 minutes to complete.
Comments/Special Instructions
Intended to be completed by the individual or parent.
The PII was originally validated in children ages 7-18 with chronic pain in Sweden (Holmstrom et al., 2015). It has also been validated for administration in English language in individuals 6-25 years old with chronic pain and Neurofibromatosis Type I or Cancer (Martin et al., 2015). Parental report was also validated in this group (Martin et al., 2015).
CP-specific Pain Category: Pain Interference
CP-specific ICF Domain: Activity and Participation (World Health Organization, 2001).
Scoring and Psychometric Properties
Scoring: 6 questions total with a 0-6 scale; 0 indicates no pain interference and higher scores indicate more pain interference. Maximum score is 36 (Martin et al., 2015).
Psychometric Properties:
In the Swedish version, the individual items included in the PII were found to have a high level of internal consistency, as measured by a Cronbach's alpha of 0.82 to 0.86 with an overall score of 0.856 (Holmstrom et al., 2015). There were no differences in PII scores between boys and girls, though older children tended to have higher scores. Moderate correlations of the PII were found with pain intensity and the Functional Disability Inventory - Parent Report and a high correlation with a depression scale were also found.
In the English version, validation was done involving participants with neurofibromatosis and cancer and their parents. Cronbach's coefficient alpha was 0.84 (unstandardized) for the patient PII, and 0.94 and 0.96 for the parent PII (mothers and fathers, respectively) (Martin et al., 2015). Parents indicated significantly more interference of pain on mood and sleep than children/adolescents. PII also demonstrated good construct validity by high correlation with the Modified Brief Pain Inventory.
Easy to administer and quick to fully complete. Can be completed by children as young as 6 years and those with learning disabilities (Martin et al., 2015). This questionnaire evaluates impact of pain on function.
Future longitudinal research is needed to determine the PII's test-retest reliability and its sensitivity to change (Martin et al., 2015).
There are long-standing concerns about the validity of children's self-report pain intensity data, so cautious interpretation is warranted (Martin et al., 2015). Differences were noted in report of pain interference with mood and sleep by children versus their parents.
Validation studies have primarily involved individuals identifying as Caucasian. Thus, impact of differing ethnicities or cultures on report of pain interference is not known.
Key References:
HolmstrÖm L, Kemani MK, Kanstrup M, Wicksell RK. Evaluating the Statistical Properties of the Pain Interference Index in Children and Adolescents with Chronic Pain. J Dev Behav Pediatr. 2015 Jul-Aug;36(6):450-4.
Martin S, Nelson Schmitt S, Wolters PL, Abel B, Toledo-Tamula MA, Baldwin A, Wicksell RK, Merchant M, Widemann B. Development and validation of the English Pain Interference Index and Pain Interference Index-Parent report. Pain Med. 2015 Feb;16(2):367-73.
Additional References:
Tedroff K, Gyllensv?rd M, LÖwing K. Prevalence, identification, and interference of pain in young children with cerebral palsy: a population-based study. Disabil Rehabil. 2021 May;43(9):1292-1298.
Treadwell MJ, Franck LS, Vichinsky E. Using quality improvement strategies to enhance pediatric pain assessment. Int J Qual Health Care. 2002 Feb;14(1):39-47.
Wicksell RK, Melin L, Lekander M, Olsson GL. Evaluating the effectiveness of exposure and acceptance strategies to improve functioning and quality of life in longstanding pediatric pain--a randomized controlled trial. Pain. 2009 Feb;141(3):248-257.
World health Organization (2001). International Classification of Functioning, Disability and Health (ICF) Retrieved 19August2021
Document last updated August 2022