St. Mark’s incontinence score for assessment of anal incontinence following obstetric anal sphincter injuries (OASIS)
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- Roos, A., Sultan, A.H. & Thakar, R. Int Urogynecol J (2009) 20: 407. doi:10.1007/s00192-008-0784-7
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The aim of this study was to assess the correlation between St. Mark’s incontinence score (SMIS) for anal incontinence and impact on quality of life (QoL), following primary repair of obstetric anal sphincter injuries (OASIS). Three hundred sixty-eight women who sustained OASIS completed a Manchester Health Questionnaire (MHQ) and the clinician calculated a SMIS. Spearman’s correlation coefficients were calculated, and Mann–Whitney U test was used to compare different severity subgroups. Mean follow-up was 10 weeks and mean age was 30 years. Mean SMIS was 1.35. All MHQ QoL domains showed statistically significant positive correlation with SMIS. When comparing SMIS subgroups (0–4, 5–8, >8), mean QoL domain scores were higher with increasing SMIS. This shows that the objective assessment of severity of anal incontinence, using the SMIS, correlates to its impact on QoL in a relatively young population with low severity of symptoms and can, therefore, be used in women who sustain OASIS.
KeywordsAnal incontinenceManchester Health QuestionnaireObstetric anal sphincter injurySt. Mark’s incontinence scoreThird- and fourth-degree tear
Anal incontinence can have a devastating effect on a woman’s emotional, social, and physical well-being and, consequently, on quality of life (QoL). A cross-sectional survey in community-dwelling subjects over 40 years of age assessed the prevalence of fecal incontinence and the impact of bowel symptoms on certain aspects of QoL . Overall, in both men and women, 52% of subjects with major incontinence and 16% of those with minor incontinence reported a considerable impact of bowel symptoms on QoL. Three percent of women reported monthly or more frequent leakage from the bowel and the prevalence increased with age from 1.2% in 40–49 years to 8.1% in 80+ years.
Several scoring systems have been designed to quantify and objectively assess anal incontinence in symptomatic patients [2–6] both as a measure of comparison between cohorts as well as measuring changes following interventions. The St. Mark’s incontinence score (SMIS)  has shown the highest correlation with the physician’s clinical impression of the severity of anal incontinence when compared to three other scoring systems [4–6] in patients suffering from fecal incontinence referred for anorectal physiological testing.
The main focus of continence scoring systems is on the physical aspects of anal incontinence, but it is questionable whether this correlates with the impact of anal incontinence on QoL. Studies to establish this relationship were mostly done in a middle-aged or older population who were either seeking medical attention for fecal incontinence [7, 8], admitting to anal incontinence at a gynecology clinic visit , or those who were evaluated after anal or rectal surgery [10–13]. In a study including 259 subjects with longstanding fecal incontinence , an increase in SMIS was related to more reported problems in usual activities, pain/discomfort, and anxiety/depression. Furthermore, there was a significant but moderate correlation between SMIS and patients’ subjective perception of bowel control, irrespective of the type of incontinence .
However, women who sustain obstetric anal sphincter injuries (OASIS) and report symptoms of anal incontinence in the postpartum period are mostly young and healthy and have predominantly minor symptoms and, therefore, differ from subjects in most previous studies. A study focusing on primiparous women living in Quebec showed that an increase in severity of anal incontinence, as measured by the SMIS, was associated with lower QoL scores . However, in this study, the SMIS was self-administered by the patient. Another study, conducted in primiparous women 6 months after delivery, showed increasing severity of fecal incontinence, as measured by the Fecal Incontinence Severity Index (FISI), was associated with poorer scores of some measures of QoL, but not all .
The aim of this study was to assess whether the SMIS, a severity score measured by the clinician, correlates with the disease-specific impact on different domains of QoL following postpartum primary repair of OASIS by obstetricians.
Materials and methods
Consecutive women attending our perineal clinic for follow-up after primary repair of OASIS were included in this study. As part of the normal protocol, patients completed a Manchester Health Questionnaire (MHQ)  and the clinician calculated a SMIS  as part of the patient’s evaluation. The MHQ is a validated disease-specific QoL questionnaire assessing the effect of bowel problems on different domains that include general health, incontinence impact, role, physical function, social function, personal function, emotional problems, sleep/energy, and severity measures. Each domain is scored from 0 to 100, a higher score indicating a greater impairment of health-related QoL. The validated SMIS is based on the type and frequency of anal incontinence (gas, liquid, solid) and its impact on daily life, the need to wear a pad or plug, the use of constipating medication, and the lack of ability to defer defecation for 15 min. The types of anal incontinence and its impact on daily life are scored from 0 (never) to 4 (daily), the need to wear protection and the use of medication 0 (no) or 2 (yes), and fecal urgency 0 (no) or 4 (yes). This gives a total score from 0 (complete continence) to 24 (complete incontinence).
For analysis, three severity subgroups were formed based on SMIS: 0–4, 5–8, and >8. Previous studies that have correlated the SMIS with the impact on QoL using severity subgroups were done in symptomatic populations. We, therefore, could not use the same severity subgroups in our analysis. The single complaint of fecal urgency is scored 4 points, and this is why our first cutoff value was 4. We took the equivalent of this to get our next cutoff value of 8. As the expected prevalence of symptoms in our population was low, we opted not to divide our population into more groups as the number of patients in each group would be too small for meaningful analysis.
Spearman’s correlation coefficient was calculated for all different MHQ QoL domains and the total SMIS. Mann–Whitney U test was done to compare mean QoL domain scores for the different SMIS severity subgroups. A p value <0.05 was considered significant.
The MHQ forms part of our routine prospective evaluation of women who sustained OASIS. All women gave written consent to use the data from questionnaires for scientific publications, and this was sanctioned by the Croydon Local Research and Development Committee.
A total of 368 women were included in this study. Their mean age was 30 years (SD 5.4 years), and the mean follow-up time was 10.3 weeks (SD 7.4 weeks) after delivery.
Mean score (standard deviation) for each MHQ QoL domain (n = 368)
Correlation between MHQ QoL domain score and SMIS (n = 368)
Women who sustained OASIS can be at high risk of developing anal incontinence. A review of the literature has revealed that, despite a primary repair, 39% continue to suffer from anal incontinence at variable time points . At 3 months postpartum, 50% of women who sustained OASIS complained of some degree of anal incontinence . Different scoring systems [14, 15, 18] have been used to evaluate the severity of anal incontinence after OASIS, including the SMIS . Although the SMIS was associated with diminished QoL in patients seeking medical help for fecal incontinence [7,8] and in primiparous women 6 months after delivery , to the best of our knowledge, no study has correlated the SMIS to a validated QoL questionnaire in women with OASIS.
Our study has shown that the SMIS has a measurable positive and statistically significant correlation with all MHQ QoL domain scores in women who sustained OASIS. Although the correlation coefficient is small, a fact possibly caused by the large group of asymptomatic women in our population, it indicates that increasing severity of anal incontinence, as measured by the clinician, correlates with an increasing impact of bowel symptoms on QoL. The SMIS includes two items that assess QoL: the impact of anal incontinence on lifestyle and the need to wear pads or plugs. When excluding these items from the total SMIS, Spearman’s correlation coefficient was similar and remained statistically significant for all MHQ QoL domains. However, this could be explained by the fact that very few women suffered from severe incontinence.
For comparison between different SMIS severity, we divided patients into three subgroups. This also showed that with increasing severity of anal incontinence the patient’s QoL is more affected.
The MHQ was developed and validated to assess health-related QoL in women with anal incontinence and is supposed to be of practical use in the evaluation of women after childbirth . It has been previously shown that significantly higher (worse) scores of two items of the MHQ, i.e., incontinence impact and severity measures, were associated with fecal incontinence, as assessed by the FISI, in primiparous women 6 months after delivery . The limitation of the MHQ, and therefore of our study, is that although it is a disease-specific questionnaire, responses could be affected by other comorbidities such as pain and bleeding. By contrast, the SMIS is not influenced by any comorbidity and can be calculated easily by the clinician. A second limitation of the MHQ is that while the QoL component has been validated, the part relating to severity of bowel symptoms has not been validated. We have found that a large percentage of women completed one question (“is the leakage from your bowel solid?”) wrongly and this needed to be rectified by the clinician when interviewing the patient.
The incidence of symptoms of anal incontinence was low in our population; with 75% of patients being asymptomatic and only 16 women (4%) scoring >8 on the SMIS. Our results show that the SMIS for anal incontinence can be used in a population with low severity of symptoms such as women being followed up after primary repair of OASIS. Objective assessment of severity of fecal incontinence by the physician, using the SMIS, correlates to the impact of bowel symptoms on patients’ QoL in a relatively young population with low severity of symptoms. While the SMIS may be difficult for patients to complete themselves, it is short and easy to complete by the physician in a busy clinical setting. Therefore, in the absence of a condition-specific scoring system for postpartum women, we recommend the use of the SMIS in the follow-up of women after primary repair of OASIS.
Conflicts of interest