Outcome Measures Used to Assess Response
INTRODUCTION
In the past, doctors recommended a particular treatment because, in their experience, most patients said that they were
“better” after receiving it. In the last two decades, we have real- ized that this is not good enough. We need objective measures by which we can determine what percentage of patients are
“cured” (normal), or at least have greater than 50% reduction in symptoms, after any given treatment.
In this century, outcome measures are going to become even more important, because there is not enough money to fund all health care. Doctors (and administrators) must assess whether one treatment is more effective than another, so that money can be spent on that which is most effective. This is loosely termed
“health economics”.
In the 1980s, continence clinicians began to realize the importance of outcome measures. It was a time of great creation.
Many different outcome measures were created, but not neces- sarily fully “validated”. The process of validation involves the fol- lowing steps.
䊏 Establish the validity of the test, that it measures what it is supposed to.
—Includes three subsets; content validity, construct validity, and criterion validity.
䊏 Establish the reliability of the test.
—For questionnaires, measure internal consistency of differ- ent parts of test.
—For questionnaires and other physical tests, the repro- ducibility, or test–retest reliability needs to be proven.
䊏 Establish the responsiveness to change of the test, before and after treatment.
This chapter provides a brief overview of outcome measures that have been validated. Most are used in this book to describe the effectiveness of different treatments.
The Standardization Committee of the International Continence Society (ICS) is the main body that has governed terminology and outcome measures in the field of urinary incontinence since 1978.8The urodynamic measures described in the previous chapter, and the pelvic floor assessments (Oxford Score and POPQ) described in Chapter Two, are also used as outcome measures. The tests described in this chapter do not require physical examination or invasive procedures.
The World Health Organization has recently acknowledged the global importance of incontinence, by holding a regular International Consultation on Incontinence (ICI) (Abrams et al1–3). These publications also consider which treatments are the most effective, as judged by standardized outcome measures.
Finally, the Cochrane Collaboration performs meta-analyses of randomized controlled trials in the field of incontinence, which also use the outcome measures described in this text.
The ICS recommends that there should be five main groups, or “domains” of outcome measures.
1. Patient’s observations (symptoms)
2. Quantification of symptoms (eg urine loss on diary or pad test) 3. Physician’s observations (anatomical and functional)
4. Quality of life measures 5. Socioeconomic evaluations
TESTS THAT MEASURE PATIENT’S SYMPTOMS
The ICIQ-SF was validated under the auspices of the ICI. It records incontinence symptoms and severity, with a simple quality of life question. The final ICIQ comprises three scored items (Figure 5.1, maximum score 21) and an unscored self- diagnostic item.
FIGURE5.1. The ICIQ-SF Questionnaire.
The Wexner Score for Fecal Incontinence
This was originally a 20-point score concerning three types of incontinence with one question for impact upon lifestyle (italic bold in Table 5.1). Later a score for wearing pads, taking consti- pating medication, or suffering from fecal urgency were added (ordinary typeface in Table 5.1). The Wexner Score has been fully validated10and is used worldwide.
TESTS THAT QUANTIFY PATIENTS’ SYMPTOMS
Rather than giving the patient a questionnaire about her symp- toms, the following tests actually measure symptoms such as stress leak, urge leak, frequency, or nocturia.
BLADDER CHART
The Bladder Chart is a generic term used to indicate several types of records.
䊏 The micturition chart only asks patients to record times of voiding and incontinence episodes; only output is considered, roughly.
䊏 The frequency volume chart (FVC) also asks patients to record their fluid intake and the volume they void, and when they change pads, usually over three days.
䊏 The urinary diary includes the details of the FVC but also includes symptoms and activities at leakage episodes, includ- ing urgency, coughing, lifting, and others.
The micturition chart tells nothing about people who drink too much (>3 liters per day) or too little (<1.5 liters per day). Most clinicians use the Frequency Volume Chart (see Figure 5.2). Although the Urinary Diary (Figure 5.2) provides even more detail about the type of leakage, patients often object to the detail required, depending on how many days of charting you require.
The FVC is a useful outcome measure. It tells you:
TABLE5.1. Modified Wexner Fecal Incontinence Score
Never Rarely Sometimes Weekly Daily
Incontinent 0 1 2 3 4
solid stool
Incontinent 0 1 2 3 4
liquid stool
Incontinent 0 1 2 3 4
to gas
Alters lifestyle 0 1 2 3 4
No Yes
Need to wear pad/plug 0 2
Take constipating meds 0 2
Unable to defer 15 min 0 2
䊏 The number of leakage episodes per 24 hours (in mild cases, convert to leaks per week by taking an average of the three days).
䊏 The number of voids per day (“frequency”).
䊏 The episodes of nocturia.
䊏 Whether patients are fluid restricting for fear of urge leak.
FIGURE 5.2. A urinary diary from a patient with urge incontinence.
Patient drinks little (1.065 l/day), has marked frequency (11 voids/day), nocturia× 2, and a small bladder capacity (average of 12 voids = 108 ml).
Note that diary gives the extra details that she leaks with urge, laughing, and running water. Note the caffeine intake.
The ideal duration of the FVC is controversial. The seven-day diary is the most sensitive and accurate, but patients dislike this burden, so compliance is poor. Because the first three days and the last four days of a seven-day test correlate well (r= 0.9), most clinicians use a three-day FVC, at least at the first visit. The ICI Committee for Research Methodology found that in most cases, a single 24-hour diary is sufficient. In our Unit, we use a three- day FVC for the first visit, and a 24-hour Urinary Diary for followup visits (see discussion of bladder training in Chapter 7).
THE PAD TEST
The One-Hour Pad Test
This was initially the “industry standard” after its introduction in 1983 and ICS recommendation in 1988. This test involves:
䊏 Patients attend with a comfortably full bladder.
䊏 Are given a pre-weighed continence pad.
䊏 Then drink 500 ml of water over 15 minutes.
䊏 Then perform a standard series of activities to provoke leakage.
䊏 The voided volume is then measured and the wet pad is re-weighed.
Unfortunately, the one-hour pad test fails to correlate with other measures of severity (poor criterion validity) and has poor sensitivity (up to 40% false negative rate). For many years, the one-hour pad test was the only objective method that could be used to define mild (1–10 g leakage per 1 hour), moderate (11–
50 g/hr), and severe (>50g/hr) incontinence; thus it is used in many publications quoted in this text.
The 24-Hour Pad Test
Because of the problems with the 1-hour test, the 24-hour home pad test was developed in the late 1980s. This test involves the following.
䊏 Women are given a set of pre-weighed pads in sealed bags.
The pads are worn at home for 24 hours. Ordinary provoca- tive activities are carried out.
䊏 They return pads in a sealed plastic bag, personally or by post, to be re-weighed.
There is no loss of accuracy by evaporation from the sealed plastic bag for durations of 72 hours to two weeks. Thus wet pads
can be returned via post. The 24-hour pad test is more sensitive than the 1-hour test (10% false negative rate).
Normal ranges for the 24-hour pad test have been contro- versial. Studies from 1989–1996 in small samples of women (n= 23–78), using simple kitchen scales, gave normal values of 3–8 grams. This seems a lot of fluid on the underwear to be tolerated by an asymptomatic woman. However this definition of “conti- nent” (up to 8 grams) is used throughout most studies in this book.
Recently6the normal values were redefined (n= 120) using scales accurate to 0.1 g. A median value of 0.3 g (95th centile 1.3 g) was obtained.
The definition of mild, moderate, and severe is important.
Because conservative therapy is more likely to cure patients with mild incontinence, and surgery is often offered to patients with severe leakage, a pad test should be able to define severity.
Recently mild, moderate, and severe were characterized as 1.3–20 g, 21–74 g, and >75g on the 24 hour test.9
Tests That Measure Anatomical and Functional Observations by Doctors
䊏 The Oxford score for measuring pelvic floor muscle strength and the POPQ scoring system for measuring prolapse were shown in Chapter 2.
䊏 The standard urodynamic test measurements were shown in Chapter 4.
QUALITY OF LIFE
A large array of Quality of Life (QOL) tests have been used in urogynecology.
䊏 Generic tests, that just measure overall QOL, are often used to provide a comparison with other medical therapies (eg cardiac surgery). The SF36 is the most common.
䊏 For incontinence, the two most common are the Urogenital Distress Inventory (UDI) and the Incontinence Impact Ques- tionnaire (IIQ), from the United States. Both come in a short form and have been fully validated. The Kings Health Ques- tionnaire is also often used (from the United Kingdom, avail- able in many languages). For full review see Abrams.1,2,3 䊏 In order to perform a health economic analysis, a QOL
test that scales from 1–100 needs to be used, such as the York Questionnaire or the AQOL (for review see Hu et al, 2005).
SOCIOECONOMIC EVALUATION
䊏 A standard test for measuring the personal and treatment costs of incontinence is the Dowell Bryant Incontinence Cost Index (DBICI), which is validated.4
䊏 Another common test is the Willingness to Pay questionnaire, usually tailormade for the particular condition.
CONCLUSIONS
In later chapters in this text, studies that employ validated outcome measures are emphasized, but in the absence of objec- tive data, some studies presenting mainly subjective data are mentioned.
References
1. Abrams P, Khoury S, Wein A, eds (1998) Incontinence: Report of World Health Organisation, 1998; Health, Plymouth UK.
2. Abrams P, Cardozo L, Koury S, Wein A, eds (2001) Incontinence:
Report of World Health Organisation, 2001, Health, Plymouth, UK.
3. Abrams P, Cardozo L, Koury S, Wein A, eds (2005) Incontinence:
Report of World Health Organisation, 2005, Health, Plymouth, UK.
4. Dowell CJ, Bryant CM, Moore KH, Simons AM (1999) Calculation of the direct costs of urinary incontinence: The DBICI, a new test instru- ment. Br J Urol 83:596–606.
5. Hu TW, Wagner TH, Hawthorne G, Moore KH, Subak L (2005) Eco- nomics of incontinence. In: Abrams P, Cardozo L, Koury S, Wein A (eds). Report of World Health Organisation.
6. Karantanis E, O’Sullivan R, Moore KH (2003) The 24-hour pad test in continent women and men: Normal values and cyclical alterations.
Br J Obstet & Gynaecol 110:567–571.
7. Karantanis E, Fynes M, Moore KH, Stanton SL (2004) Comparison of the ICIQ-SF and 24-hour pad test with other measures for evalu- ating the severity of urodynamic stress incontinence. Int Urogynecol J 15:111–116.
8. Lose G, Fantl A, Victor A, Walter S, Wells T, Wyman J et al (1998) Outcome measures for research in adult women with symptoms of lower urinary tract dysfunction. Neurourol Urodyn 17:255–262.
9. O’Sullivan R, Karantanis E, Stevermuer TL, Allen W, Moore KH (2004) Definition of mild, moderate and severe incontinence on the 24-hour pad test. Br J Obstet Gynaecol 111:859–862.
10. Vaisey C, Garapeti E, Cahill J, Kamm M (1999) Prospective compar- ison of faecal incontinence grading systems. Gut 44:77–80.
