Psychometric Characteristics of the Pain Treatment Satisfaction Scale

1
Psychometric Characteristics of the Pain
Treatment Satisfaction Scale

• Robyn L. Walker1, Michael E. Clark1,2,
• Ronald J. Gironda1,2
• 1 James A. Haley Veterans Hospital
• 2 University of South Florida
• Tampa, Florida

2
Introduction

• Recognition of the importance of health-related
  treatment outcomes in general and pain-related
  outcomes in particular, has been growing. The
  foundation for this increased focus on pain
  treatment outcomes stems from the fact that
  effective pain assessment and treatment requires
  the availability of valid and reliable measures
  of pain-related dysfunction and treatment outcome
  (Clark Gironda, 2002). There exist several
  reliable, valid, and comprehensive pain
  assessment instruments including the
  Multidimensional Pain Inventory (Kerns, Turk,
  Rudy, 1985), and the Pain Outcomes Questionnaire
  (POQ) (Clark, Gironda, Young, 2003) suitable
  for tracking treatment-related changes across
  multiple outcomes domains.
• One important and infrequently studied
  pain-related outcome is patient satisfaction with
  treatment services, for which there are currently
  no validated self-report measures. The Pain
  Treatment Satisfaction Scale (PTSS) was developed
  to fill this gap in outcomes measurement for
  chronic pain treatment. The PTSS consists of
  5-items from the post-treatment version of the
  POQ-VA. Previous research has found the PTSS to
  have good internal consistency and good
  concurrent and predictive validity (Clark,
  Gironda, Young, 2003). However, further
  research is needed to bolster the psychometric
  validity and establish the construct validity of
  the PTSS. The purpose of the current study was to
  evaluate the psychometric characteristics of the
  PTSS, with a focus on establishing construct
  validity through examining concurrent outcomes
  variables.

3
Method

• Participants
• Participants consisted of 202 individuals with
  chronic non-cancer pain admitted between 12/02
  and 12/04 to a CARF-accredited, 18-day, inpatient
  interdisciplinary pain treatment program at a
  southeastern Veterans Administration Hospital.
  The majority of participants were military
  veterans, although several veteran spouses
  participated. Characteristics of the sample are
  reported in Table 1.
• Measures
• Pain Treatment Satisfaction Scale (PTSS). The
  PTSS consists of 5-items from the post-treatment
  version of the POQ-VA. Previous research has
  found the PTSS to have good internal consistency
  and good concurrent and predictive validity
  (Clark, Gironda, Young, 2003). At a 3 month
  follow-up appointment, patients were asked to
  rate their overall satisfaction with their pain
  treatment and whether they would recommend the
  program to others on a scale of 0 to 10.
• Pain Outcomes Questionnaire-VA Version (POQ-VA).
  The POQ-VA (Clark, Gironda, Young, 2003) is a
  self-report instrument that assesses pain
  intensity and pain-related difficulties in five
  outcomes domains (activities of daily living,
  mobility, negative affect, vitality and
  pain-related fear). The subscales possess
  excellent generalizability, acceptable
  test-retest reliability, good convergent and
  discriminant validity, and acceptable sensitivity
  to change. The POQ-VA was administered at program
  admission, discharge, and 3 month follow-up.

4
Method Continued

• Measures Continued
• Minnesota Multiphasic Personality Inventory
  Revised (MMPI-2). The MMPI-2 (Butcher, Graham,
  Ben-Porath, Tellegen, Dahlstrom, Kaemmer, 2001)
  is a widely accepted and empirically validated
  self-report inventory that assesses major
  patterns of personality and psychological
  disorders. The MMPI-2 content scales of
  Depression, Anxiety, and Health Concerns were
  selected due to previous research demonstrating
  their association with pain treatment outcomes.
• Procedure
• Participants completed the MMPI-2 and the POQ-VA
  as part of their initial treatment evaluation.
  Program graduates then completed the POQ-VA
  (including the PTSS), at the time of discharge
  and at a 3 month follow-up appointment. Data were
  gathered and analyzed for those participants who
  completed the pain treatment program and the
  required questionnaires. Staff ratings of patient
  satisfaction and improvement also were utilized
  in the analyses.

5
Table 1. Demographic Characteristics
6
Results

• Reliability and Factor Analysis of the PTSS
• Reliability analyses with the five item PTSS
  were conducted. Calculation of coefficient alphas
  revealed that the scale has excellent internal
  consistency (a .9124). Reliability analyses are
  reported in Table 2 and indicated that intra-item
  and item-total correlations ranged from moderate
  (r .58) to high (r .80). A factor analysis
  was then performed utilizing the 5-items on the
  PTSS in a Principal-Components analysis, which
  revealed a one-factor solution accounting for
  74.16 of the variance.
• Correlational Analyses with the POQ-VA z-scores
• Correlations between the PTSS and POQ-VA
  discharge and three month follow up scores were
  computed and are presented in Table 3. Z-scores
  were calculated for each scale on the POQ-VA and
  were summed to approximate a global measure of
  pain related dysfunction or impairment. This
  POQ-VA global z-score was utilized in all the
  correlational analyses. As illustrated in the
  table, higher PTSS Discharge Total, Follow-Up
  Overall, and Follow-Up Recommend scores were
  associated with decreased reports of global
  pain-related impairment or dysfunction as
  measured by the POQ-VA global z-score.

7
Table 2. PTSS Reliability Analyses
8
Table 3. Correlations Between PTSS POQ-VA
global z-score at Discharge and Follow Up
9
Results Continued

• Correlational Analyses with the MMPI-2
• Correlations between the PTSS and selected
  MMPI-2 scales were run computed and are presented
  in Table 4. Interestingly, the only MMPI-2 scale
  that was found to be significantly associated
  with any PTSS score was the Health Concerns scale
  at discharge.
• Correlational Analyses with Staff Ratings
• Correlations between staff ratings and the
  PTSS at discharge and satisfaction ratings at
  three month follow-up were conducted and are
  displayed in Table 5. As shown in the table,
  staff ratings of patient satisfaction and
  improvement were highly associated with patient
  ratings of satisfaction at discharge and three
  month follow-up.

10
Table 4. Correlations Between PTSS Selected
MMPI-2 Content Scales
11
Table 5. Correlations Between PTSS Staff
Ratings at Discharge and Follow Up
Staff Ratings
Patient Report Patient Satisfaction Patient Improvement
PTSS Discharge .420 .289
Overall Follow Up Satisfaction .342 .296
Recommend Program Follow Up .267 .274
12
Results Continued

• Multiple Regression Analyses
• A set of three hierarchical multiple
  regressions were conducted to examine the
  predictive utility of the POQ-VA global z-score
  and the selected MMPI-2 scales. In the first
  analysis, the PTSS discharge total score served
  as the dependent variable, in the second analysis
  the Follow-Up Overall Satisfaction score was the
  dependent variable, and in the final analysis the
  Follow-Up Recommend score was the dependent
  variable. To control for differences in
  variations in participant age and education,
  these variables were entered in Block 1.
  Similarly, to control for the effects of
  pre-existing personality constructs, the MMPI-2
  Depression, Anxiety, and Health Concerns content
  scales, were entered in Block 2. Finally, POQ-VA
  global z-score was entered in Block 3. This
  procedure provided a means to compare the unique
  contribution of the POQ-VA (at discharge and 3
  month follow-up) into the prediction of PTSS
  scores (at discharge and 3 month follow-up,
  respectively) while controlling for other
  potential systematic sources of variance. The
  results of these analyses are presented in Table
  6. As is evident in the table, POQ-VA discharge
  and follow-up global z-scores were significant
  predictors of patient satisfaction at discharge
  and at 3 months follow-up. Interestingly, no
  MMPI-2 content scales significantly contributed
  to the prediction of patient satisfaction.

13
Table 6. Hierarchical Regression Analyses of POQ
z-scores and MMPI-2 scales on PTSS at discharge
and follow-up
14
Discussion

• In the current study, the psychometric
  characteristics of the previously developed five
  item Pain Treatment Satisfaction Scale (PTSS)
  were evaluated in a large sample of chronic pain
  patients who had recently completed an eighteen
  day interdisciplinary pain management program.
  Reliability analyses conducted with the PTSS
  indicated that individual item-total correlations
  were high and overall internal consistency was
  strong. A Principal Components analysis of the
  PTSS items yielded a single-factor solution
  accounting for 74.16 of the variance.
• Concurrent outcome variables, including the
  POQ-VA, MMPI-2, and staff ratings of patient
  satisfaction and improvement, were utilized to
  evaluate the construct validity of the PTSS.
  Analyses determined that the PTSS showed modest
  to strong correlations with measures of related
  constructs. Staff ratings of patient satisfaction
  and improvement and a composite POQ-VA score at
  discharge and three month follow-up, were all
  found to be strongly associated with patient
  satisfaction with the pain management program.
  Additionally, at a three month follow-up, patient
  ratings of whether they would recommend the
  program to someone with a similar problem were
  found to be related to lower ratings of discharge
  and follow-up pain related impairment and higher
  ratings of satisfaction with the program.

15
Discussion Continued

• Interestingly, analyses that utilized the
  MMPI-2 content scales of Depression, Anxiety, and
  Heath Concerns to evaluate the effects of
  selected pre-morbid personality characteristics
  and emotional symptoms demonstrated that
  pre-existing personality constructs had limited
  impact on patients satisfaction with their pain
  treatment. Rather, improvements in pain-related
  impairments and dysfunction achieved during
  treatment were more strongly associated with
  patient satisfaction.
• The results of these analyses provide support
  for the psychometric integrity and clinical
  utility of the five-item PTSS as a measure of
  patient satisfaction with pain treatment.
  However, the veteran sample utilized in this
  study may not be representative of individuals
  with chronic pain encountered in other settings.
  Since it is possible that the PTSS would perform
  differently in other patient populations,
  replication of these findings in non-veteran
  community samples is necessary in order to
  establish its overall validity and utility.

16
References

• Butcher, J. N., Graham, J. R., Ben-Porath, Y. S.,
  Tellegen, A., Dahlstrom, W. G., Kaemmer, B.
  (2001). MMPI-2 Manual for administration,
  scoring, and interpretation. (Rev. ed.).
  Minneapolis, MN University of Minnesota Press.
• Clark, M. E., Gironda, R. J. (2000). Concurrent
  validity of the National Pain Data Bank
  Preliminary results. American Journal of Pain
  Management, 10, 25-33.
• Clark, M. E., Gironda, R. J. (2002). Practical
  utility of outcome measurement. R. S. Weiner
  (Ed.), Pain management A practical guide for
  clinicians (6th ed., ). Boca Raton, FL. CRC
  Press.
• Clark, M.E., Gironda, R.J., Young, R.W. (2003).
  Development and validation of the Pain Outcomes
  Questionnaire- VA. Journal of Rehabilitation
  Research Development, 40,(5), 381-395.
• Gironda, R. J., Azzarello, L., Clark, M. E.
  (2002). Test-retest reliability of the National
  Pain Data Bank V. 2.0. American Journal of Pain
  Management, 12, 24-30.
• Kerns, R. D., Turk, D. C., Rudy, T. E. (1985).
  The West Haven-Yale Multidimensional Pain
  Inventory (WHYMPI). Pain, 23, 345-356.