Supplementary Material A: RECORD Statement
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BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any reliance Supplemental material placed on this supplemental material which has been supplied by the author(s) BMJ Open Supplementary Material A: RECORD Statement The RECORD statement – checklist of items, extended from the STROBE statement, that should be reported in observational studies using routinely collected health data. Item STROBE items Location in RECORD items Location in manuscript where No. manuscript where items are reported items are reported Title and abstract 1 (a) Indicate the Page 1 in title and RECORD 1.1: The type of data 1.1 Page 1 in the abstract. study’s design with abstract used should be specified in the a commonly used title or abstract. When possible, term in the title or the name of the databases used the abstract (b) should be included. Provide in the 1.2 Page 1 in the abstract. abstract an RECORD 1.2: If applicable, informative and the geographic region and balanced summary timeframe within which the of what was done study took place should be and what was found reported in the title or abstract. 1.3 Page 1 – data were linked in a system wide dataset. RECORD 1.3: If linkage between databases was conducted for the study, this should be clearly stated in the title or abstract. Introduction Background 2 Explain the Page 3 under rationale scientific Introduction background and rationale for the investigation being reported Objectives 3 State specific Page 3 at the bottom objectives, including of the page. any prespecified hypotheses Methods Study Design 4 Present key elements Page 4 under 2.1 Data, of study design early application and in the paper setting. Setting 5 Describe the setting, Page 4 locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data collection Participants 6 (a) Cohort study - Cross-sectional study RECORD 6.1: The methods of In this case all individuals within Give the eligibility – page 4 gives study population selection BNSSG registered to a criteria, and the eligibility criteria and (such as codes or algorithms contributing practice were sources and methods sources/method of used to identify subjects) included for analyses. Therefore of selection of selection. should be listed in detail. If this codes to identify the overall study participants. is not possible, an explanation population were not used. Describe methods of should be provided. follow-up For the high-risk group Case-control study - RECORD 6.2: Any validation population selection, all codes Give the eligibility studies of the codes or and criteria used are listed fully in criteria, and the algorithms used to select the Supplementary Material B and sources and methods population should be the methods described in section of case referenced. If validation was 2.2 (page 4). ascertainment and conducted for this study and control selection. not published elsewhere, Furthermore, the resulting list Give the rationale detailed methods and results was compared with estimated for the choice of should be provided. expected numbers of high-risk cases and controls individuals described in the Cross-sectional RECORD 6.3: If the study Discussion under interpretation study - Give the involved linkage of databases, page 11. eligibility criteria, consider use of a flow diagram and the sources and or other graphical display to The system-wide dataset at methods of selection demonstrate the data linkage BNSSG CCG is already linked of participants process, including the number for analyses but a reference is included providing further 1 Kenward C, et al. BMJ Open 2020; 10:e041370. doi: 10.1136/bmjopen-2020-041370 BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any reliance Supplemental material placed on this supplemental material which has been supplied by the author(s) BMJ Open (b) Cohort study - of individuals with linked data information to the dataset For matched studies, at each stage. (Reference 25) and linking give matching through a pseudonymised ID criteria and number (unique individual identifier) was of exposed and mentioned on page 4. unexposed Case-control study - For matched studies, give matching criteria and the number of controls per case Variables 7 Clearly define all All outcomes and RECORD 7.1: A complete list All outcomes and variables are outcomes, variables are fully of codes and algorithms used to fully defined including the use of exposures, defined including the classify exposures, outcomes, algorithms and coding lists in predictors, potential use of algorithms and confounders, and effect Supplementary Material B for the confounders, and coding lists in modifiers should be provided. high-risk criteria and effect modifiers. Supplementary If these cannot be reported, an Supplementary Material C for all Give diagnostic Material B for the explanation should be clustering and non-clustering criteria, if high-risk criteria and provided. variables. applicable. Supplementary Material C for all clustering and non- clustering variables. Reference to the Supplementary material included on page 5 of the methods. Data sources/ 8 For each variable of Table C.3 in measurement interest, give sources Supplementary of data and details of Material C. methods of assessment (measurement). Describe comparability of assessment methods if there is more than one group Bias 9 Describe any efforts To minimise to address potential misclassification and sources of bias information bias, high risk criteria and coding lists were subject to double clinical review (page 5 Methods). The discussion page 10,11 discusses potential information bias as a limitation of using routine datasets. Study size 10 Explain how the Page 4 and 5 study size was arrived at Quantitative 11 Explain how How the variables variables quantitative were operationalised variables were for analyses is detailed handled in the in Table C.3 analyses. If Supplementary applicable, describe Material C. which groupings were chosen, and why Statistical 12 (a) Describe all a) Section 2.3 page 5. methods statistical methods, Further details on including those used cluster analysis and to control for selection of the confounding number of clusters is (b) Describe any included in methods used to Supplementary examine subgroups Material C. and interactions (c) Explain how b) Subgroups were missing data were investigated in Table addressed 2 Kenward C, et al. BMJ Open 2020; 10:e041370. doi: 10.1136/bmjopen-2020-041370 BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any reliance Supplemental material placed on this supplemental material which has been supplied by the author(s) BMJ Open (d) Cohort study - If 1. Methods described applicable, explain on page 5. how loss to follow- up was addressed c) Page 5 Case-control study - If applicable, d) NA. The full explain how BNSSG cohort from matching of cases March 2019 was taken and controls was for analyses. addressed Cross-sectional e) Sensitivity analyses study - If applicable, in terms of the describe analytical clustering solution methods taking chosen for account of sampling segmentation is fully strategy described in (e) Describe any Supplementary sensitivity analyses Material C. Also described more briefly in the methods page 5. Data access .. RECORD 12.1: Authors should The full BNSSG database and cleaning describe the extent to which the population for the SWD were methods investigators had access to the used for analyses. This is database population used to included on page 4. create the study population. RECORD 12.2: Authors should provide information on the data How variables were coded and cleaning methods used in the operationalised is documented in study. Supplementary Material B and C and page 4 describes how a unique identifier is used to link data between the tables in the system wide dataset. Linkage .. RECORD 12.3: State whether Page 4 under section 2.1. the study included person-level, institutional-level, or other data linkage across two or more databases. The methods of linkage and methods of linkage quality evaluation should be provided. Results Participants 13 (a) Report the Page 6 for descriptive RECORD 13.1: Describe in Page 6 for descriptive analyses. numbers of analyses. detail the selection of the Page 8 for cluster analysis. individuals at each Page 8 for cluster persons included in the study stage of the study analysis. (i.e., study population (e.g., numbers selection) including filtering potentially eligible, based on data quality, data examined for availability and linkage. The eligibility, selection of included persons confirmed eligible, can be described in the text included in the and/or by means of the study study, completing flow diagram. follow-up, and analysed) (b) Give reasons for non-participation at each stage. (c) Consider use of a flow diagram Descriptive 14 (a) Give Page 6 for descriptive data characteristics of analyses. study participants Page 8 for cluster (e.g., demographic, analysis. clinical, social) and information on Number of exposures and participants with potential missing data page 8. confounders (b) Indicate the number of participants with missing data for 3 Kenward C, et al. BMJ Open 2020; 10:e041370. doi: 10.1136/bmjopen-2020-041370 BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any reliance Supplemental material placed on this supplemental material which has been supplied by the author(s) BMJ Open each variable of interest (c) Cohort study - summarise follow- up time (e.g., average and total amount) Outcome data 15 Cohort study - Cross-sectional study Report numbers of – Page 6, Table 1, outcome events or Figure 1 and 2 report a summary measures comparative analysis over time of the low, moderate Case-control study - and high-risk groups Report numbers in with regard to each exposure demographic and category, or socioeconomic summary measures information, historical of exposure healthcare utilisation, Cross-sectional and burden of study - Report comorbidity.