We analyzed pooled baseline data from 1141 subjects in 3 randomized trials, CARE, OPUS, and ATLAS, conducted by the Pelvic Floor Disorders Network, (PFDN), an NIH sponsored multi-center network. These clinical trials used standardized tools including the POPQ, the Pelvic Floor Distress Inventory (PFDI) and the Pelvic Floor Impact Questionnaire (PFIQ) 4
. The CARE study enrolled women planning sacrocolpopexy for stage 2-4 prolapse without symptoms of stress incontinence and completed follow-up in 2005 5, 6
; the OPUS study enrolled stress continent women with anterior vaginal prolapse undergoing vaginal surgery and is ongoing 7
; and the ATLAS study enrolled women with stress incontinence and stage 0-2 vaginal support and completed follow-up in 2008 8
. Each clinical site and the data coordinating center received institutional review board approval for these studies, and all subjects provided written informed consent.
The POPQ measurements Aa, Ba, Ap, Bp and C have positive values when the prolapse extends beyond the hymen and negative when the particular points remain proximal to the hymen. We created three composite measures of support loss (SL) as summary measures, SL3 (includes TVL, C, Ba and Bp), SL5 (includes TVL, C, Aa, Ba, Ap and Bp), and SLmax (includes location of single most distal point) ().
Equations for Three Summary Scores for Support Loss
When there is perfect support, POPQ points Aa, Ba, Ap and Bp equal minus 3; thus, the support loss formulas add 3 to each of these values so that, in a situation of perfect support, the resulting measurement of support loss would equal zero. In regard to C (cervix or vaginal cuff), we added this value to total vaginal length (TVL); in a situation of perfect support, the negative C would be similar to TVL and result in a value near zero. We note that in women with a cervix in situ, perfect support may mean that negative C is not the same as TVL since the cervix is anterior and distal to the TVL measurement in the cul-de-sac. contains the equations for the three definitions tested in this analysis.
Each support loss measure was correlated with several measures of pelvic symptoms and severity, as well as condition-specific life impact: the Pelvic Organ Prolapse Quantification (POPQ) system stage 3, 9
, total scores for responses to the Pelvic Organ Prolapse Distress Inventory (POPDI) and the Pelvic Organ Prolapse Impact Questionnaire (POPIQ), and responses to questions 4 (“usually have a sensation of bulging or protrusion”) and 5 (“usually have a bulge or something falling out seen/felt”) of the Pelvic Floor Distress Inventory (PFDI) 4
. Pearson correlation coefficients and associated p-values are reported. The relationships between POPQ stage with the support loss measures, POPIQ and POPDI were assessed using one-way ANOVA.
In order to assess the utility of these support loss measures to describe long-term anatomical outcomes, only two-year CARE data 10
were used (as the ATLAS and OPUS studies only assessed one year outcomes). The change in each support loss measure, as well as POPQ stage from baseline to 24 months, was calculated. The relative responsiveness of each measure was evaluated using the standardized response mean (SRM). SRM, a commonly used statistic of responsiveness, is defined as the mean change in score over a time period divided by the standard deviation of individuals' changes in scores11
. A higher SRM (in absolute value) is indicates better responsiveness. A value of 0.5 is a cutoff for moderate responsiveness, 0.8 good responsiveness, and 1.0 excellent responsiveness 11
. Pearson correlation coefficients were calculated for the change from baseline to 24 months in support measures and POPQ stage with corresponding changes in POPDI and POPIQ.
All reported p-values were based on the two-sided statistical tests and intended to be interpreted from a hypothesis-generating framework. The analyses were performed in SAS 9.1.3 for Windows (SAS Inc., Cary, NC).