Source: J Urol 1999 Aug;162(2):369-375
The National Institutes of Health chronic prostatitis
symptom index: development and validation of a new outcome measure.
Chronic Prostatitis Collaborative Research Network.
Litwin MS, McNaughton-Collins M, Fowler FJ Jr, Nickel JC, Calhoun EA,
Pontari MA, Alexander RB, Farrar JT, O'Leary MP.
Department of Urology, University of California, Los Angeles, USA.
Chronic abacterial prostatitis is a syndrome characterized by pelvic
pain and voiding symptoms, which is poorly defined, poorly understood,
poorly treated and bothersome. Research and clinical efforts to help men
with this syndrome have been hampered by the absence of a widely accepted,
reliable and valid instrument to measure symptoms and quality of life
impact. We developed a psychometrically valid index of symptoms and quality
of life impact for men with chronic prostatitis.
MATERIALS AND METHODS:
We conducted a structured literature review of previous work to provide
a foundation for the new instrument. We then conducted a series of focus
groups comprising chronic prostatitis patients at 4 centers in North America,
in which we identified the most important symptoms and effects of the
condition. The results were used to create an initial draft of 55 questions
that were used for formal cognitive testing on chronic prostatitis patients
at the same centers. After expert panel review formal validation testing
of a revised 21-item draft was performed in a diverse group of chronic
prostatitis patients and 2 control groups of benign prostatic hyperplasia
patients and healthy men. Based on this validation study, the index was
Analysis yielded an index of 9 items that address 3 different aspects
of the chronic prostatitis experience. The primary component was pain,
which we captured in 4 items focused on location, severity and frequency.
Urinary function, another important component of symptoms, was captured
in 2 items (1 irritative and 1 obstructive). Quality of life impact was
captured with 3 items about the effect of symptoms on daily activities.
The 9 items had high test-retest reliability (r = 0.83 to 0.93) and internal
consistency (alpha = 0.86 to 0.91). All but the urinary items discriminated
well between men with and without chronic prostatitis.
The National Institutes of Health chronic prostatitis symptom index provides
a valid outcome measure for men with chronic prostatitis. The index is
psychometrically robust, easily self-administered and highly discriminative.
It was formally developed and psychometrically validated, and may be useful
in clinical practice as well as research protocols.