The reported prevalence of overactive bladder has varied widely in earlier studies due to differences in symptom assessment, study population, data collection, and definition of overactive bladder including exclusion criteria.
Few studies have had the opportunity to link a large population data collection to temporal data in terms of the use of services such as hospitals.
The following data will be systematically extracted, by independent pairs of reviewers, under the following main headings: methods, population, data collection, data synthesis (themes and supporting quotations), results, discussion, conclusions and recommendations.
From each included study we obtained information on author, country, study type, study population, data collection and ascertainment method(s), age of study subjects, and whether the estimate was point or period prevalence.
The selected themes were then translated into quality indicators (i.e. with standardized specifications detailing the eligible population, data collection procedures, numerator and denominator), using the quality indicators found in the systematic literature review in the first phase.
8 9 When reporting intervention studies of this type in the scientific literature, the authors are normally required to focus on the descriptions of the sample population, data collection procedures, results, statistical analyses and the conclusions obtained from the studies.
However, as quality indicators, they do not have standardized specifications detailing the eligible population, data collection procedures and types of analysis needed to calculate them [ 24] (see Table 1).
The criteria that must be met by registries participating in EUROCAT include a definition of the population, data collection and ascertainment, definition and coding of defects, calculation of prevalence rates, and confidentiality [ 8].
Our study highlights the importance of standardisation of the methods used for storage and staining of tumour tissue as well as the patient population, data collection and determination of clinical end points.
Firstly, concerning the population, data collection and definition of non-compliance, we cannot exclude a population selection bias since a proportion of women were not included (refusal or non response) and we included probably more patients from hospitals with high volumes (but regional data are available for comparison concerning all stages of cancer, metastatic and non-metastatic BC).
