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Table 5 Key characteristics and instrument development evidence supporting content validity

From: Patient-reported outcome labeling claims and measurement approach for metastatic castration-resistant prostate cancer treatments in the United States and European Union

 

BPI-SF worst pain item

BPI-SF average pain item

PPI (from MPQ)

FACT-P

Key characteristics

    

Type of measure

Symptom: pain

Symptom: pain

Symptom: pain

PC-specific HRQOL

Constructs/subscales

Pain intensity (or severity): worst paina

Pain intensity (or severity) average pain

Present pain intensity

FACT-G subscales:

▪ Physical well-being

▪ Social well-being

▪ Emotional well-being

▪ Functional well-being

Plus PC subscale (12 site-specific items to assess prostate related “additional concerns”)

Number of items

1

1

1

39 (27 FACT-G; 12 PC specific)

Recall period

Past 24 hours

Unspecified

Present

Past 7 days

Response scale

0-10 NRS

0-10 NRS

0-6 VRS

5-point Likert scale

Instrument development: support for content validity

    

Patients with mCRPC included in development process

–/✓a

–a

–a

–/✓b

Input from clinicians or HCPs treating patients with mCRPC included in development measure

–

–

–

–

Items of importance to patients with mCRPC identified from literature review during instrument development

–

–

–

–

  1. BPI-SF = Brief Pain Inventory–Short Form; FACT-G = Functional Assessment of Cancer Therapy–General; FACT-P = Functional Assessment of Cancer Therapy—Prostate Module; HCP = health care professional; HRQOL = health-related quality of life; mCRPC = metastatic castration-resistant prostate cancer; MPQ = McGill Pain Questionnaire; NRS = numeric rating scale; PC = prostate cancer; PPI (from MPQ) = Present Pain Intensity component of the McGill Pain Questionnaire; VRS = verbal rating scale.
  2. ✓= Yes, evidence identified; − = No evidence identified.
  3. aGater and colleagues evaluated the content validity of the BPI-SF “average pain” and “worst pain” items (both assessed on a 0–10 numeric rating scale) in cognitive debriefing interviews with 17 patients with mCRPC [[21]]. Results strongly supported content validity for the “worst pain item” in this population. However, there was variability in patients’ interpretation of the “average pain” item, so results did not support the content validity of this item in patients with mCRPC. The MPQ PPI (assessed on a 0–6 VRS) was also evaluated. Patients’ interpretation of the PPI item was variable, and they also had difficulty with the VRS [[21]].
  4. bAccording to Esper and colleagues, eight individuals with PC contributed to item development, and 25 individuals with PC at various stages and 10 additional patients with PC who had undergone radical prostatectomy completed and provided feedback on the first draft of the FACT-P [[18]]. However, the exact number of patients with mCRPC included during development was not reported. Based on a personal communication with the instrument developer, Dr. David Cella, most patients participating in the Esper study were men with early stage disease and only some had advanced, metastatic and castrate-resistant disease [[18]].
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Health and Quality of Life Outcomes

ISSN: 1477-7525

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