dc.description.abstract |
Faecal incontinence (FI) is a socially stigmatised condition that can have a devastating impact on its sufferers. It is associated with substantial economic burden to communities. Despite having a profound impact on quality of life, individuals are often reluctant to report their symptoms for fear of embarrassment. This, along with the lack of consistently used definitions and widely varying study methodologies, has made estimating the extent of the problem in populations difficult. The accurate assessment of the prevalence of FI has important implications for the development of treatments and services, which are known to be effective in the management of FI. As with many other societies around the world, the prevalence of FI in New Zealand is unknown. The initial aims of this thesis were to review existing studies to determine why a wide range of prevalence estimates (0.4%-19.5%) exists and what definitions for FI have been used in the past. The research also aimed to perform a national study to investigate the prevalence of FI in New Zealand, accounting for different risk factors and using a validated assessment tool. Acknowledging the unique New Zealand environment where multiple health disparities are known to exist between the indigenous Māori and non- Māori this study also sought to use the equal statistical power methodology to investigate differences in FI that may exist between these two groups. The systematic review of literature revealed that the above variation in prevalence estimates could be explained by differences in data collection method and two factors within definitions of FI: type of stool and frequency of FI episodes. When these factors were accounted for, the FI prevalence at a threshold of at least once per month for liquid or solid stool was 8.3–8.4 per cent for face-to-face or telephone interviews, and 11.2– 12.6 per cent for postal surveys. FI was observed to be an unvoiced symptom, with lower rates of prevalence reported in personal interviews compared with anonymous postal questionnaires. The New Zealand Bowel Control Study Questionnaire was sent by post to an agestratified sample of 4200 New Zealanders (2200 of Mäori descent and 2000 non-Mäori), aged 18 and over, selected randomly from the electoral roll. The sample was selected to allow the calculation of prevalence estimates for the national population. Various methods were used to increase response rate in the study of this sensitive topic - including multiple mailouts, postcard reminders and telephone follow up. The overall response rate was 60.4%. Response rate was dependent on ethnicity, age and deprivation score measured through NZDep index. The prevalence of FI by symptoms “accidental leakage of liquid or solid stool at least 1-3 times per month” was 12.6%. Analysis of different definitions to estimate prevalence revealed that differences exist between those that feel they have a problem, their symptoms and the effects of FI on their quality of life. A new definition was proposed to incorporate these domains. Māori ethnicity, increasing age, previous anal surgery, deprivation score, diabetes, decreased mobility, neurological disorder, and third or fourth degree obstetric tear, were identified as associated with FI within the New Zealand community, with all except age and ethnicity significant on multivariate analysis. The following conditions were also noted to be associated with FI: irritable bowel syndrome, constipation, haemorrhoids and urinary incontinence. The significant difference in prevalence noted between Māori and non-Māori (17.9% vs 12.0% p<0.001), was explained in part by diabetes and deprivation score. Addressing this disparity identified for Māori deserves special focus and attention in research, public policy and healthcare delivery in the future. The uncertainty around the relationship between childbirth and FI was clarified, with analysis indicating that sphincter injury in the form of episiotomy or tear is the most significant factor associated with FI, over and above parity, prolonged labour and instrumental delivery. It was revealed that less than one in three individuals discussed their loss of bowel control with their family doctor or other healthcare professional, reaffirming the stigma associated with FI and reinforcing the need to break down the barriers to gaining help and the taboo associated with discussing defecation. Overall, FI has been identified as a common problem in New Zealand, the extent of which was previously unknown. It is envisaged that this research has advanced understanding to ensure that those suffering from this condition in community populations are better identified, not neglected and able to receive appropriate management. |
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