Note from the National Guideline Clearinghouse (NGC): A systematic review of the literature was prepared by the Minnesota Evidence-based Practice Center (EPC) for the Agency for Healthcare Research and Quality (AHRQ) for use by the National Institutes of Health (NIH) (see the "Availability of Companion Documents" field).
Quality Assessment and Rating the Body of Evidence
Study quality was analyzed using the following criteria: subject selection, length and loss of follow-up, adjustment for confounding factors in observational studies and intention to treat principle in clinical trials, masking the treatment status, randomization scheme and adequacy, allocation concealment, and justification of sample sizes in randomized controlled trials (RCTs).
The level of evidence for all studies was estimated using a subset of the U.S. Preventive Services Task Force criteria (see the "Rating Scheme for the Strength of the Evidence" field).
For all questions, evidence tables were developed identifying the purpose of the study, sample, design, independent and dependent variables, and findings. For Questions 1, 2, and 3, incidence and prevalence cases of incontinence, relative risk of incontinence in categories of risk factors and clinical interventions, and outcomes level to assess severity and progression of incontinence for treatment differences were abstracted. Baseline data were compared in different studies to test differences in the target population and unusual patterns in the data. Standard deviations, regression coefficients, and 95 percent confidence interval (CI) were calculated from reported means, standard errors, and sample size. The protocol for the meta-analyses was created according to recommendations for meta-analysis of randomized controlled trials: the QUOROM statement.
Data Extraction
Evaluations of the studies and data extraction were performed manually and independently by three researchers. The data abstraction forms are shown in Appendix E of the Evidence Report (see the "Availability of Companion Documents" field). Errors in data extractions were assessed by a comparison with the established ranges for each variable and the data charts with the original articles. Any discrepancies were detected and discussed. Patient populations were classified as community and long-term care (LTC) settings. Adjustments for patient age, race, gender, comorbidities, socioeconomic status, provider characteristics, and clustering of patients and providers were extracted from the studies. The details on extracted variables are presented in the analytic framework in Appendix A of the Evidence Report (see the "Availability of Companion Documents" field).
Data Synthesis
For Questions 1 and 2, results of individual studies (expressed as crude and adjusted for confounding factors) were summarized in evidence tables to analyze differences in incontinence in categories by subject age, race, ethnicity, residency, and risk factors.
Definitions of Incontinence
Urinary, fecal, and combined incontinence were analyzed separately. EPC staff used the definitions of signs and symptoms of urinary incontinence (UI) promoted by the International Continence Society (ICS) (refer to Appendix A of the Evidence Report [see the "Availability of Companion Documents" field]) including mixed, stress, and urge incontinence. Anal incontinence (AI) was defined as involuntary loss of flatus, liquid, or solid stool. In the text, the term fecal incontinence (FI) was used and in the tables, the operational definitions of anal (flatus and fecal), FI, solid, or liquid incontinence, or its combinations were clarified. Continence was defined as self-reported absence of involuntary urine or feces loss. Combined incontinence was defined as a combination of urine and fecal incontinence. Frequency of UI or FI was abstracted as daily, weekly, or monthly episodes of urine leakage or feces loss. Severity of UI was defined using the objectively measured urine loss in pad weight tests or self-reported pad use. Severity of FI was defined as self-reported amount of feces loss and pad use. Wet status in nursing home residents was analyzed to define severity of incontinence and effects of the treatments.
Definitions of Outcomes
EPC staff defined prevalence of incontinence as the probability of experiencing incontinence within a defined population and at a defined time point. True population incidence was defined as newly diagnosed cases of incontinence that developed annually in the target population. True population incidence estimates were derived from large population-based surveys. However, for Question 3 incidence was defined as the probability of developing incontinence under study after active and control interventions during time of follow-up. Reported incontinence was defined as the prevalence of total incontinence or episodes of different types of incontinence when the authors did not access continence status as baseline or did not exclude prevalence cases from overall estimation.
The absolute risk of incontinence among patients with rare risk factors was compared to the general population when no other evidence was available to estimate the adjusted relative risk (RR).
For Question 3, RR and 95 percent CIs and differences in outcomes were calculated.
Patient Outcomes (Clinical Events)
EPC staff report both incidence and progression of incontinence as they were used by the authors of the original studies and with calculated rates of cure, improvement, and progression for purposes of comparison:
- The number of patients that developed newly diagnosed incontinence (incidence cases) or the number of incontinent patients after active and control interventions (prevalence cases)
- The number of patients cured by the clinical interventions
- The number of patients with improved continence
- The number of patients with progression defined as failure to cure or improve and increase in frequency and severity of incontinence
Relative risk/odds ratio of developing incontinence was analyzed in the studies that reported incident cases. Relative risk/odds ratio of incontinence was analyzed in the studies that reported prevalence cases. Relative benefit of continence was defined as the likelihood of continence in patients after active treatment relative to those after control interventions. Relative benefit of improvement was defined as a likelihood of improved incontinence in patients after active treatment relative to those after control interventions. Relative risk of progression of incontinence was defined as the likelihood of increasing frequency and severity of incontinence and failure to cure/improve incontinence in patients after active treatment relative to those after control interventions.
Continence was analyzed separately from improvement in incontinence because continence is the most clinically desirable patient outcome and is well defined, whereas improvement can include substantial differences in definitions and changing perceptions of qualitative and quantitative parameters of improvement. Such conservative approaches were used to generate precise estimates of the effectiveness.
Continuous Outcomes (Surrogates)
Subjective continuous outcomes were defined as the number of incontinent episodes, use of supplies, and scores from validated scales to analyze the quality of life with incontinence. Objective continuous outcomes were defined as the results of objective tests to measure the severity of incontinence.
Pooling criteria included the same operational definitions of incontinence outcomes and the same risk factors or clinical interventions. Homogeneity in clinical interventions was analyzed comparing published information on behavioral, instrumental (devices), pharmacological, and surgical treatments. Meta-analysis was used to assess the consistency of the association between treatments and incontinence outcomes with random effects models. The analyses were conducted separately for symptoms and signs of incontinence. Assumptions underlying meta-analysis included valid measurements of continence status and similarity in study and target populations.
Refer to Chapter 2, "Methods" in the Evidence Report (see the "Availability of Companion Documents" field) for more information.
