The Wisconsin Stone Quality of Life questionnaire (WISQOL) is a disease-specific health-related quality of life (HRQOL) instrument designed to assess the impact on patients of stones in the urinary tract (urolithiasis). Although urolithiasis has long been associated with bothersome symptoms, severe pain, emergency and urgent care encounters, reduced productivity, sleep interruptions, increased financial burden, and interruptions to the performance of daily activities, a disease-specific instrument to assess the symptomatic and functional impact of stones has never been developed. The WISQOL is thus the only such instrument in existence.
Urolithiasis is a common condition, affecting nearly 10% of the population; 1 its prevalence is therefore the same as diabetes. The lifetime risk of kidney stones approaches 20% in men and 10% in women. While the incidence of kidney stones in the U.S. is rising overall, this rise is especially significant among women. 2-4 Children are not immune; data show that the incidence of kidney stones in children is also rising. 4,5 In all individuals, recurrence of stones is the norm. Depending on age, comorbidities, and other factors, up to 75% will experience at least one additional stone event within their lifetime.6 Those with recurrent stones frequently undergo repeated surgical interventions, require life-long medications, and are expected to return annually or more frequently for clinical follow-up. The annual cost of kidney stones in the U.S. is estimated at $10 billion, making it the most expensive urologic condition in the U.S. 7 While usually referred to as “benign,” urolithiasis is anything but. Recent data suggest that recurrent kidney stones are associated with a higher incidence of chronic kidney disease and end-stage renal disease. 8 Given its high rate of recurrence and the inability to predict stone events, urolithiasis has long been recognized as a chronic condition.
The concept of HRQOL has evolved over the past 30 years to encompass the physical and mental factors of peoples’ health. Disease-specific HRQOL describes the impact of specific diseases on patients. Many chronic conditions – including diabetes, hypertension, asthma, arthritis, osteoporosis, and heart disease – have long had instruments for assessing HRQOL. Recently, interest in the HRQOL of patients with recurrent urinary stones has risen, coinciding with health care reforms placing greater emphasis on patient-reported outcomes and on endpoints of medical and surgical therapy that encompass patient well-being and satisfaction.
But, prior to the WISQOL, there was no standardized measure for assessing the symptomatic and functional impact of urolithiasis. We began to develop the WISQOL after observing that patients with urolithiasis scored lower for HRQOL on the SF-36v2 Health Survey 9 (a validated, 36-item, generic health and well-being questionnaire) than U.S. normals. Interestingly, women scored lower for HRQOL than men, suggesting that women may suffer differently from kidney stones. This finding was published:
Since then, others have used the SF-36 to replicate and confirm our findings. But we were interested in not just the general but the stone-related impact on patients’ HRQOL. We realized that a generic HRQOL instrument would never reveal this and set out to develop one specific for urolithiasis.
We conducted cognitive interviews and held focus groups with more than 30 of our patients in an effort to identify areas of greatest concern. Additionally, we consulted with urologists, nephrologists, and advanced practice urology providers to document problems and symptoms patients had described to them. The focus group and patient interview findings were then categorized according to theme. Specific items within each theme were developed using the words patients themselves used to describe their symptoms. Patient feedback about these 60+ items, including patients’ assessments of their importance as well as the frequency with which they experienced them, were documented and analyzed. Ultimately, a 32-item questionnaire, later shortened to 28 items, was developed and tested in 250 patients. Details of this process were published:
We continued to use the WISQOL in the urology clinic at UW Health University Hospital to further confirm its clinical utility. Two additional papers were published:
We then went on to prospectively test and validate the WISQOL focusing on its internal consistency, reliability, and concurrent validity. We assembled a consortium of initially 8 urology centers in the U.S. and Canada (the number has currently risen to 12) to join us in assessing the WISQOL. The North American Stone Quality of Life consortium recently published a paper describing the psychometric properties of the WISQOL administered to nearly 1,600 patients.
We wanted to know if the WISQOL could predict changes in patients’ HRQOL over time. Data from the North American Stone Quality of Life Consortium, now nearing 1,800 patients, was analyzed and showed that the WISQOL is indeed capable of detecting changes. For example, patients with symptomatic stones at the time they completed the first WISQOL largely scored higher at second completion (3 months to 1 year) if their stones had either passed or been surgically removed. The opposite was also found to be true. Although more studies are needed, this provides preliminary evidence that the WISQOL is responsive, which is a measure of its validity. As we work on a paper to further describe these findings, an abstract along these lines was presented at the annual meeting of the American Urological Association (May 2016; San Diego, CA).
- Penniston KL, Tennyson LE, Averch TD, Viprakasit DP, Antonelli JA, Sivalingam S, Sur RL, Chew BH, Pais Jr VM, Bird VG, Nakada SY: The Wisconsin Stone Quality of Life questionnaire: follow-up results from a prospective, longitudinal, multi-center validation study of the health-related quality of life of patients with kidney stones. Journal of Urology 2016;195:E284
We continue to deepen our understanding of how patients with kidney stones, especially recurrent, are affected, including by exhaustive surgical procedures that may render patients “stone-free” but which may actually undermine their HRQOL. We also continue to encourage urologists and other providers who treat patients for kidney stones to prioritize patients’ HRQOL and to consider it the ultimate endpoint for measuring treatment success.
Currently we are working on further validation studies and on confirming the most appropriate scoring system for the WISQOL. Proposals to translate the instrument to other languages are also being entertained.Finally, sub-studies within the North American Stone Quality of Life Consortium are looking at: how patients’ HRQOL, as measured with the WISQOL, correlates with stress (as measured with a validated stress questionnaire); whether patients on long-term stone prevention medications have higher HRQOL than patients not treated with these medications; how different surgical stone removal modalities affect patients’ HRQOL; and differences in patients’ HRQOL based on race/ethnicity, socioeconomic status, age, and other factors. Using the WISQOL, answers to questions about how different groups of people are affected by kidney stones may become available. In sum, we anticipate that the WISQOL will be useful not only to clinicians wishing to assess the impact of medical and/or surgical stone management on their patients but also to researchers who may use patients’ stone-related HRQOL as a primary outcome measure in clinical trials.
Educational and non-profit use is free, but must be registered. License fees for commercial use of the WISQOL for testing any intervention with potential for-profit application must be negotiated with the Wisconsin Alumni Research Foundation.
- Scales CD, Smith AC, Hanley JM, et al: Prevalence of kidney stones in the United States. Eur Urol 2012;62:160-5
- Strope SA, Wolf JS Jr, Hollenbeck BK: Changes in gender distribution of urinary stone disease. Urology 2010;73:543-6
- Penniston KL, McLaren ID, Greenlee RT, et al: Urolithiasis in a rural Wisconsin population from 1992 to 2008: narrowing of the male-to-female ratio. J Urol 2011;185:1731-6
- Tasian GE, Ross ME, Song L, et al: Annual incidence of nephrolithiasis among children and adults in South Carolina from 1997 to 2012. Clin J Am Soc Nephrol 2016;11:488-96
- Dwyer ME, Krambeck AE, Bergstralh EJ, et al: Temporal trends in incidence of kidney stones among children: a 25-year population based study. J Urol 2012;188:247-52
- Moe OW: Kidney stones: pathophysiology and medical management. Lancet 2006;367:333-44
- Kirkali Z, Rasooly R, Star RA, et al: Urinary stone disease: progress, status, and needs. Urology 2015;86:651-3
- Rule AD, Krambeck AE, Lieske JC: Chronic kidney disease in kidney stone formers. Clin J Am Soc Nephrol 2011;6:2069-75
- Ware JE JR, Kosinski M, Bayliss MS, et al: Comparison of methods for the scoring and statistical analysis of SF-36 health profile and summary measures: summary of results from the medical outcomes study. Med Care 1995;33:AS264-79