Is urinary incontinence associated with vulval lichen sclerosus in women? A cross‐sectional study
Authors: L. Kirby, S. Gran, F. Orekoya, C. Owen, R. Simpson
Journal: British Journal of Dermatology (2021)

Dear Editor, Increasing evidence suggests that the pathogenesis of male genital lichen sclerosus (LS) is driven by chronic, occluded exposure of susceptible epithelium to the irritant effect of urine.1, 2 It is not clear how this can be extrapolated to women; however, the typical 'figure of eight' distribution seen in female genital LS suggests that urine could be implicated. This has not yet been robustly investigated.3 This study utilized data prospectively entered into the East Lancashire Hospitals NHS Trust vulval dermatology database between 2017 and 2020. Cross-sectional analysis was performed to determine the odds of urinary incontinence (UI) in LS, compared with other genital conditions in adult female patients. The LS group comprised women with genital LS, diagnosed clinically and/or histologically. The non-LS group consisted of women with genital conditions other than LS, identified from the same clinic. UI was screened for using the validated International Consultation on Incontinence Questionnaire (ICIQ) Urinary Incontinence Short Form.4 Power calculation demonstrated that for 90% power and 5% error to detect a 20% difference, 110 patients would be needed per group. Ethical approval was not required as the data were unlinked and anonymous. All patients were assessed by a consultant dermatologist with a specialist interest in vulval disease. Clinical diagnosis (plus histological if available), demographics, body mass index (BMI), parity and ICIQ score were recorded. Age was identified as an a priori confounder; BMI and parity were potential confounders.5 The associations between potential confounders and LS and UI status were analysed using the two-sample t-test for normally distributed data or the Mann–Whitney U-test for non-normally distributed data. Univariate logistic regression was conducted to determine the association between LS and UI. Multivariable logistic regression using the 10% change in the adjusted odds ratio (OR) was used to assess for confounding and to obtain a final model, which included all confounders. Sensitivity analyses were conducted excluding patients with LS/lichen planus (LP) overlap and irritant contact dermatitis secondary to UI. The most common diagnoses in the non-LS group were eczema, candidiasis, vulvodynia and irritant contact dermatitis. The baseline characteristics of all participants (n = 384) are presented in Table 1. The prevalence of UI was 63% in the LS group and 34% in the non-LS group, P < 0·001. Women with LS were significantly older (median 62 vs. 50 years, P < 0·001). The LS group had higher BMI (median 29 vs. 26 kg m−2, P < 0·001) and parity (both median 2, interquartile range 2–3 vs. 0–2, P < 0·001). The LS group reported lower washing frequency per day than the non-LS group (both median 1, interquartile range 1–1 vs. 1–2, P = 0·047). Parity and BMI were significantly associated with both LS and UI status. Participants with missing data for these variables or UI status were excluded from the final analysis (n = 31); 353 participants were included in the multivariable analysis (LS n = 112, non-LS n = 241). BMI and parity were not found to be confounders using the 10% rule. The unadjusted OR for UI was 3·85 [95% confidence interval (CI) 2·40–6·18], P < 0·001. The final age-adjusted OR was 2·56 (95% CI 1·55–4·24), P < 0·001. Sensitivity analysis excluding LS/LP overlap (n = 8) from the LS group increased the age-adjusted OR to 2·80 (95% CI 1·67–4·70), P < 0·001. When irritant contact dermatitis secondary to UI (n = 21) was excluded from the non-LS group, the OR was 3·15 (95% CI 1·87–5·30). Excluding both of these groups, the age-adjusted OR was 3·55 (95% CI 2·10–6·04), P < 0·001. To our knowledge, this is the first study using a validated screening tool for UI and prospectively collected data, which is powered to determine the odds of UI in vulval LS. The prevalence of UI was 63% and the odds were increased 2·5-fold. Few studies have reported the prevalence of UI in women with LS. A recent meta-analysis found a pooled prevalence of 0·35 (95% CI 0·13–0·58), comparable with that of the general population.3 Our LS population was similar to those in two previous cross-sectional studies.5, 6 Increased age and parity were reported in women with LS compared with other vulval conditions, as well as controls, in both of these studies,5, 6 one of which also reported higher BMI.5 In women of comparable age and BMI to our LS population, 46% of women aged 60–64 years7 and 50% of those with BMI 25–29 kg m−2 had UI.8 Less frequent washing in women with LS is an interesting finding; however, discussion is beyond the scope of this letter. The strengths of this study were the use of a validated screening tool for UI, and diagnosis by an expert clinician, with histological confirmation when required. The entire database was utilized to minimize selection bias. Data were collected from a single centre; therefore, the study population and secondary care setting may limit generalizability. A key limitation associated with the cross-sectional design is that the direction of association between UI and LS cannot be determined. This study provides evidence of a link between UI and vulval LS. Large population-based cohort studies are now needed to determine the nature of this association. The data that support the findings of this study and a full study report are openly available at the University of Nottingham Research Data Management Repository at http://doi.org/10.17639/nott.7114. We would like to thank Mr Pete Sagar for the database design and Mr Simon Hill for advice about evaluating urinary incontinence. Lisa Kirby: Data curation (lead); Formal analysis (lead); Funding acquisition (lead); Investigation (lead); Project administration (lead); Visualization (equal); Writing-original draft (lead). Sonia Gran: Formal analysis (supporting); Methodology (equal); Supervision (supporting); Validation (lead); Writing-review & editing (equal). Oluwafikunayo Orekoya: Investigation (supporting); Validation (supporting); Writing-review & editing (supporting). Caroline Owen: Conceptualization (equal); Investigation (supporting); Methodology (supporting); Resources (lead); Supervision (equal); Validation (supporting); Writing-review & editing (equal). Rosalind Simpson: Conceptualization (equal); Methodology (equal); Supervision (equal); Writing-review & editing (equal).