Though all summary scores include incontinence to solid stool, liquid stool, and flatus, some summary scores use equal weights, while others do not. The Wexner/CCF score weighs each item on a scale of 0 (never) to 4 (more than once per day). Thus, in this summary score, there is no judgment by the authors as to which type of incontinence is worse. Other authors chose a different approach and assigned different weights to the same frequencies of different items within the scoring tool. The authors of the Vaizey/St. Mark’s score chose lesser weight for pad use and constipating medications that reflected their belief that these items may represent a subjective fear of social embarrassment, rather than actual frequency. However, again, such a method of assigning weights may not reflect the subjective patient experience of incontinence (Baxter et al. 2003). As seen in the FISI, patients and surgeons do not value all types of incontinence in the same way; thus, using surgeon-developed weights may not reflect the patient’s experience which is paramount in describing a symptom. Thus, though conceptually intuitive, weighted summary scores add a degree of increased subjectivity. Firstly, who is the most appropriate person to assign the weights: patients or surgeons? If patients, should it be a standardized weighting, or should each individual patient set the relevant weights for themselves, that is, a self-derived weighting scheme? Although weights give additional information, they also add complexity and perhaps subjectivity to the tool, making it less practical for everyday clinical use. The most frequently cited scores are the simple non-weighted scoring systems as they are easy and practical to use.

Another approach to including the patient’s experience of the symptom, without weighting, is the inclusion of a measure of impact on the patient’s life, by including either coping mechanisms, lifestyle alteration, or some other measure of quality of life. The Wexner/CCF score includes two items which address impact: changes in lifestyle and wearing a pad. These items serve as measures of the patient’s experience of the symptom and their resultant quality of life. Similarly, the Vaizey/St. Mark’s score uses the same items, in addition to constipating medications. These measures of impact have proven to be quite important as patients may limit the severity of their incontinence by altering their lifestyle; that is, a patient might have only infrequent episodes of incontinence by severely restricting their activities so that they can be close to a bathroom at all times. Such a patient’s suffering would be appropriately detected by a tool that addresses impact but can be totally missed by a score that solely evaluates severity of incontinence. Thus, measuring impact in addition to severity can enrich our understanding of the patient’s symptom.

Some scores include other aspects of incontinence that are not solely related to sphincter function. For example, the Vaizey/St. Mark’s FIS (Table 12.6) includes urgency, the Lunniss score includes “difficulty cleaning” (Lunniss et al. 1994), and the Fecal Incontinence Severity Index (Table 12.7) includes mucous discharge. Such inclusions may not be most desirable as these symptoms are not exclusive of compromised anal sphincter function. For example, patients with severe proctitis could have mucous discharge and urgency though their underlying problem is proctitis rather than anal sphincter dysfunction.

Thresholds can be assigned to determine the level at which treatment can be useful or to predict a change in QoL with a change in symptom severity . In addition, thresholds are useful to determine the desired treatment effect and guide sample size calculations in research protocols. Such a useful threshold was determined for the Wexner/CCF score. In 2001, Rothbarth et al. evaluated 35 women with anterior sphincter defects who underwent sphincter repair. The patients completed the Wexner/CCF FIS , Gastrointestinal Quality of Life (GIQoL) index score , and the SF-36 score before and after sphincter repair. The authors found a strong correlation between a Wexner/CCF FIS greater than or equal to 10 and a lower GIQoL index and SF-36 score compared with the standard population (Rothbarth et al. 2001). Similarly, Damon and colleagues looked at clinical characteristics and quality of life in a cohort of 621 patients with fecal incontinence using the Wexner/CCF FIS and GIQoL index. They found a significant correlation between a Wexner/CCF FIS greater than or equal to 11 and the total GIQoL score. More recently, Brown et al. conducted the largest community-based fecal incontinence questionnaire to date, including 5,817 women 45 years and older (Brown et al. 2013). One of the questions asked was “Have you ever talked to a physician about accidental leakage of stool and/or gas?.” Data was available for 938 women who responded “yes,” and only 29 % of these responders with fecal incontinence reported that they sought care. Care seekers were more likely to have a primary care physician, have heard about fecal incontinence, and suffered longer with more severe leakage. Furthermore, the mean Wexner score of care seekers was 10.7 compared to non-care seekers who had a score of 7.5. Thus, a threshold of 10 or greater on the Wexner score also predicts women who seek care and predicts a significantly worse QoL.

In summary, the best and most used summary scores are the ones that balance between ease of use and a strong discriminatory ability. The Wexner/CCF and Vaizey/St. Mark’s scores both achieve this balance, as is demonstrated by their widespread use, validity, reliability, and correlation with QoL measures. Furthermore, thresholds within the summary scores allow clinicians to assess the impact of interventions and researchers to plan protocols for future treatments. Judging by the “weight” of the number of citations in peer reviewed publications, the Wexner/CCF has been more widely accepted perhaps due to its simplicity and lack of potentially subjective weightings.