Patients with autosomal dominant polycystic kidney disease (ADPKD) progressively develop fluid-filled kidney cysts; expansion of the cysts results in physically displacing and obstructing renal tubules, blood vessels, and lymphatics. The cyst expansion also promotes apoptosis, atrophy, and fibrosis of the renal parenchyma. Progression of ADPKD occurs at varying rates; in later stages ADPKD is associated with loss of kidney function.
Patients may present with hypertension, flank pain, urinary tract infection, nephrolithiasis, gross hematuria, or palpable kidneys. Later stage ADPKD may involve multiple organs and have a broad spectrum of complications. Due to its complex symptomatology, hereditary nature, and gradual progression, patients with ADPKD face significant impact on their health-related quality of life (HRQoL). There are few available data on the disease burden of ADPKD and there are no validated instruments to assess the impacts of ADPKD.
Researchers, led by Dorothee Oberdhan, MS, developed content for a new self-administered patient-reported outcome questionnaire, the ADPKD Impact Scale (ADPKD-IS). The scale was developed as a means to “comprehensively assess HRQoL in patients with ADPKD as a patient0centric valid measure,” according to the researchers. The scale was described in the American Journal of Kidney Diseases [2018;71(2):225-235].
The researchers followed standard guidelines for the development of a new patient-reported outcome instrument. Men and women ≥18 years of age were recruited via referrals from physicians and family, advocacy groups, and print advertising. Informed consent was provided prior to any study-related activities.
The study included 1674 adult patients with ADPKD: 285 patients participated in focus groups to generate content for a questionnaire; 15 patients were participated in debriefing interviews to refine the questionnaire, and 1374 patients were involved in assessment of the performance and measurement properties of the questionnaire.
Concepts relevant to HRQoL were identified using a literature review (4801 articles, 27 relevant). Patient-reported outcome instruments of possible interest to concepts related to ADPKD were also identified (kidney disease, pain, anxiety, depression, and urologic issues); instruments used in prior studies of ADPKD were also examined. There were no instruments available that had been specifically designed for use in the ADPKD population.
In consultation with 26 clinical experts from North America, Japan, and Europe, it was noted that patients with ADPKD are not typically affected by many identified concepts (physical impact, emotional impact, and urinary concerns) at early stages of disease. Concerns such as shortness of breath, difficulty eating, depression, and physical and emotional burden, increase as ADPKD progresses. Pain and discomfort were also seen as potential issues and the clinicians recommended inclusion in the patient questionnaire.
The concepts generated from the literature review and the clinical expert discussions were assessed in focus groups of patients (United States, 42; Turkey, 15; Germany, 29; United Kingdom, 20; and Japan, 11). Twenty concepts related to physical impact, emotional impact, urinary concerns, and other issues were identified.
Fifteen patients in the United States participated in cognitive debriefing interviews; resulting in an instrument with 18 items grouped into two general domains: physical impact and social/emotional impact of ADPKD. The initial concepts were confirmed as globally consistent in additional focus groups with 168 patients (North America, 31; South Korea, 16; Australia, 8; South America, 18; China, 15; Taiwan, 16; Japan, 12; Romania, 7; Spain, 16; Czech Republic, 15; Hungary, 6; and Poland, 8).
There was general agreement regarding the concepts between sexes and regions. Participants reported three distinct types of pain (sharp acute, dull chronic, and fullness/discomfort) as relevant to patients with ADPKD.
The final ADPKD-IS consisted of 14 items representing three conceptual domains: physical, emotional, and fatigue (Sidebar). The reliability (internal consistency and test-retest) and validity (content and construct) of the scale were supported in further evaluation.
The need for data resulting from more clinical use was cited as a limitation to the model by the researchers. Further evaluation of additional complex concepts such as ADPKD-related pain and impact on HRQoL is needed.
“The ADPKD-IS is a new patient-centric tool that reliably and validly provides a standardized method for assessing HRQoL and overall disease burden in patients with ADPKD,” the researchers said.
- There are no validated instruments developed specifically to assess the impact of autosomal dominant polycystic kidney disease (ADPKD) on patients’ health-related quality of life (HRQoL).
- Using consultations with clinical experts and patient focus group discussions, researchers developed content for a new self-administered patient-reported outcome questionnaire to assess ADKPD-related HRQoL.
- The ADPDK Impact Scale reliably and validly provides a standardized method for assessing HRQoL and disease burden among patients with ADKPD.