Symptom Variability and Early Symptom Regression in the MAPP Study: A Prospective Study of Urological Chronic Pelvic Pain Syndrome
We examined symptom variability in men and women with urological chronic pelvic pain syndrome. We describe symptom fluctuations as related to early symptom regression and its effect on estimated 1-year symptom change. We also describe a method to quantify patient specific symptom variability.
Materials and Methods:
Symptoms were assessed biweekly in 424 subjects with urological chronic pelvic pain syndrome during 1 year. To evaluate the impact of early symptom regression subjects were classified as improved, no change or worse according to the rate of change using 1) all data, 2) excluding week 0 and 3) excluding weeks 0 and 2. Patient specific, time varying variability was calculated at each interval using a sliding window approach. Patients were classified as high, medium or low variability at each time and ultimately as high or low variability overall based on the variability for the majority of contacts.
Prior to excluding early weeks to adjust for early symptom regression 25% to 38% and 5% to 6% of patients were classified as improved and worse, respectively. After adjustment the percent of patients who were improved or worse ranged from 15% to 25% and 6% to 9%, respectively. High and low variability phenotypes were each identified in 25% to 30% of participants.
Patients with urological chronic pelvic pain syndrome show symptom variability. At study enrollment patients had worse symptoms on average, resulting in a regression effect that influenced the estimated proportion of those who were improved or worse. Prospective studies should include a run-in period to account for regression to the mean and other causes of early symptom regression. Further, symptom variability may be quantified and used to characterize longitudinal symptom profiles of urological chronic pelvic pain syndrome.
- 1 : The MAPP research network: a novel study of urologic chronic pelvic pain syndromes. BMC Urol2014; 14: 57. Google Scholar
- 2 : The MAPP research network: design, patient characterization and operations. BMC Urol2014; 14: 58. Google Scholar
- 3 : Validation of a modified National Institutes of Health chronic prostatitis symptom index to assess genitourinary pain in both men and women. Urology2009; 74: 983. Google Scholar
- 4 : The interstitial cystitis symptom index and problem index. Urology1997; 49: 58. Google Scholar
- 5 : Pain and urinary symptoms should not be combined into one score: psychometric findings from the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network. J Urol2016; 195: 949. Link, Google Scholar
- 6 : Random-effects models for longitudinal data. Biometrics1982; 38: 963. Google Scholar
- 7 : A prospective study of interstitial cystitis: results of longitudinal followup of the interstitial cystitis data base cohort. Interstitial Cystitis Data Base Study Group. J Urol2000; 163: 1434. Link, Google Scholar
- 8 : A prospective study of symptoms and quality of life in men with chronic prostatitis/chronic pelvic pain syndrome: the National Institutes of Health Chronic Prostatitis Cohort study. Chronic Prostatitis Collaborative Research Network. J Urol2006; 175: 619. Link, Google Scholar
- 9 : Some effects of within-person variability in epidemiological studies. J Chronic Dis1973; 26: 781. Google Scholar
- 10 : The effect of regression to the mean in epidemiologic and clinical studies. Am J Epidemiol1976; 104: 493. Google Scholar
- 11 : Regression to the mean: what it is and how to deal with it. Int J Epidemiol2005; 34: 215. Google Scholar
- 12 : Effect of variability in the 7-day baseline pain diary on the assay sensitivity of neuropathic pain randomized clinical trials: an ACTTION study. Pain2014; 155: 1622. Google Scholar