Table 2

Specific points to consider when undertaking analyses and reporting safety results from biologics registers in rheumatology (right column) in addition to general recommendations for improving the reporting of observational studies (STROBE guidelines, left column*)

STROBE recommendations for improving the reporting of observational studies7Specific additional points to consider from rheumatology biologics registers
Item (N)
Title and abstract1
  1. (A)

    (A). Indicate the study's design with a commonly used term in the title or the abstract

  2. (B)

    (B). Provide in the abstract an informative and balanced summary of what was done and what was found

Introduction
 Background/rationale2Explain the scientific background and rationale for the investigation being reported
 Objectives3State specific objectives, including any prespecified hypotheses
Methods
 Study design4Present key elements of study design early in the paper
 Setting5Describe the setting, locations and relevant dates, including periods of recruitment, exposure, follow-up and data collection
  1. (A)

    (A). Provide an estimation of drug penetration in source population

  2. (B)

    (B). Describe eligibility for, and access to, treatment

  3. (C)

    (C). Indicate the time points for assessment of serial follow-up

  4. (D)

    (D). Outline calendar trends in availability of biologic/awareness of outcome

 Participants6
  1. (A)

    (A). Give the eligibility criteria and the sources and methods of selection of participants. Describe methods of follow-up

  2. (B)

    (B). For matched studies, give matching criteria and number of exposed and unexposed

  1. (A)

    (A). Provide a clear definition of the exposed and non-exposed cohorts. Justify the choice of comparator

  2. (B)

    (B). Describe whether treatment is restricted to new starts or encompasses all individuals with ongoing treatment

  3. (C)

    (C). Describe the conditions where subjects may change from one cohort to the other

  4. (D)

    (D). Describe whether treatment reflects first start until first stop of therapy or multiple treatment episodes. If the latter, discuss definition of duration of exposure and any implications for combining treatment intervals

 Variables7Clearly define all outcomes, exposures, predictors, potential confounders and effect modifiers. Give diagnostic criteria, if applicableClearly define start and stop of therapy
 Data sources/measurement8*For each variable of interest, give sources of data and details of methods of assessment (measurement). Describe comparability of assessment methods if there is more than one group
 Bias9Describe any efforts to address potential sources of bias
 Study size10Explain how the study size was arrived at
 Quantitative variables11Explain how quantitative variables were handled in the analyses. If applicable, describe which groupings were chosen and why
 Statistical methods12
  1. (A)

    (A). Describe all statistical methods, including those used to control for confounding

  2. (B)

    (B). Describe any methods used to examine subgroups and interactions

  3. (C)

    (C). Explain how missing data were addressed

  4. (D)

    (D). If applicable, explain how loss to follow-up was addressed

  5. (E)

    (E). Describe any sensitivity analyses

  1. (A)

    (A). Define and justify the risk window. Whenever possible, categorise as (1) on drug, (2) on drug + lag window or (3) ever treated

  2. (B)

    (B). The use of multiple risk attribution models and lag windows is encouraged if appropriate, but needs to be accompanied by a description of numbers and relative risks for each model

  3. (C)

    (C). If the same association under study has previously been published, consider using a similar analysis model and definitions for replicative purposes

Results
 Participants13*
  1. (A)

    (A). Report numbers of individuals at each stage of study (eg, numbers potentially eligible, examined for eligibility, confirmed eligible, included in the study, completing follow-up and analysed)

  2. (B)

    (B). Give reasons for non-participation at each stage

  3. (C)

    (C). Consider use of a flow diagram

 Descriptive data14*
  1. (A)

    (A). Give characteristics of study participants (eg, demographic, clinical, social) and information on exposures and potential confounders

  2. (B)

    (B). Indicate number of participants with missing data for each variable of interest

  3. (C)

    (C). Summarise follow-up time (eg, average and total amount)

  1. (A)

    (A). Provide additional information on average treatment duration for both treated and comparison cohorts

  2. (B)

    (B). Describe subjects who changed exposure status

  3. (C)

    (C). Provide numbers eligible for follow-up, numbers with completed follow-up and numbers remaining on treatment and/or in analysis at relevant time points during follow-up (eg, at yearly intervals). The use of tabular or graphical presentations of numbers exposed, outcomes and relative risks over time is encouraged

 Outcome data15*Report numbers of outcome events or summary measures over timeConsider the use of a tabular or graphical presentation (Kaplan–Meier, cumulative incidence plot) of the outcome over time for the exposed and comparison cohort
 Main results16
  1. (A)

    (A). Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision (eg, 95% CI). Make clear which confounders were adjusted for and why they were included

  2. (B)

    (B). Report category boundaries when continuous variables were categorised

  3. (C)

    (C). If relevant, consider translating estimates of relative risk into absolute risk for a meaningful time period

  1. (A)

    (A). Present both relative risks and absolute measures such as event rates per person-time, risk differences or numbers needed to treat/numbers needed to harm

  2. (B)

    (B). Provide information on crude as well as all adjusted measures of the main effect as well as the intrinsic effects of key confounders

  3. (C)

    (C). Present results per time period of follow-up, if applicable, so as to indicate any time dependence of the association between exposure and outcome

 Other analyses17Report other analyses done (eg, analyses of subgroups and interactions, and sensitivity analyses)
  1. (A)

    (A). Consider performing analyses to explore possible effect modification

  2. (B)

    (B). Consider performing sensitivity analyses for differing definitions of exposure (item 12A) and outcome or different statistical models, if applicable

Discussion
 Key results18Summarise key results with reference to study objectives
 Limitations19Discuss limitations of the study, taking into account sources of potential bias or imprecision. Discuss both direction and magnitude of any potential bias
  1. (A)

    (A). Selection factors for treatment should be considered and discussed

  2. (B)

    (B). Discuss implication of unmeasured/residual confounding

 Interpretation20Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of analyses, results from similar studies and other relevant evidence
 Generalisability21Discuss the generalisability (external validity) of the study results
Other information
 Funding22Give the source of funding and the role of the funders for the present study and, if applicable, for the original study on which the present article is based
  • * Reproduced with permission of the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) group.