Interpretation and content validity of the items of the Hamilton inventory to evaluate outcomes in Persian-speaking patients with complex regional pain syndrome: A cognitive interview approach

Background: The Hamilton Inventory for complex regional pain syndrome (CRPS) is a multidisciplinary assessment tool to evaluate signs and symptoms in patients with CRPS, developed in the English language.

Purpose: This study aims to translate and cross-culturally adapt this tool for Persian-speaking patients with CRPS. Furthermore, this study aimed to understand how 1) Persian-speaking experts and patients interpret and calibrate responses to items on the Hamilton Inventory and 2) compensatory strategies that might affect responses.

Study design: A cross sectional study with cognitive interview method.

Methods: Ten health care providers and 10 patients with CRPS were interviewed using cognitive interviewing techniques (talk-aloud, semi-structured interview probes). All interviews were recorded and transcribed verbatim. A directed content analysis was done to analyze the interviews using a previously established framework.

Results: Overall, the items on the Hamilton Inventory were well received by participants. Areas, where questions were unclear to some participants were recorded and categorized into five themes: Clarity and Comprehension (100%) in item 1 from the health professional tool and (65%) from the eleven items of the patient-reported tool. Perspective modifiers of culture influenced the calibrations of items "I feel my condition has negatively affected my relationships." (12%) and "My symptoms affect my comfort level with intimacy." (20%) from the patient-reported tool.

Conclusion: The findings of this study demonstrate that there is no need for substantive changes to the items of the Hamilton Inventory, as they tend to be understood by Persian-speaking experts and patients with CRPS.