Table 4.

Analysis of studies of TKAs in patients younger than 55 years using STROBE criteria

Category	Number	Item summary	Number of studies	Percentage of studies
Title	1a	Indicate the study’s design with a commonly used term in the title or the abstract	7	54%
Abstract	1b	Provide in the abstract an informative and balanced summary of what was done and what was found	12	92%
Introduction	2	Explain the scientific background and rationale for the investigation being reported	12	92%
Background	3	State specific objectives, including any prespecified hypotheses	1	8%
Methods	4	Present key elements of study design early in the paper	10	77%
	5	Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, followup, and data collection	11	85%
	6a	Give the eligibility criteria and the sources and methods of selection of participants; describe methods of followup	12	92%
	6b	Give matching criteria and numbers of [patients] treated and untreated	3	23%
	7	Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers; give diagnostic criteria, if applicable	9	69%
	8	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	0	0%
	9	Describe any efforts to address potential sources of bias	0	0%
	10	Explain how the study size was arrived at	6	46%
	11	Explain how quantitative variables were handled in the analyses; if applicable, describe which groupings were chosen, and why	4	31%
	12a	Describe all statistical methods, including those used to control for confounding	2	15%
	12b	Describe any methods used to examine subgroups and interactions	1	8%
	12c	Explain how missing data were addressed	1	8%
	12d	If applicable, explain how loss to followup was addressed	1	8%
	12e	Describe any sensitivity analyses	0	0%
Results	13a	Report the numbers of individuals at each stage of the study (eg, the numbers potentially eligible, examined for eligibility, confirmed eligible, included in the study, completing followup, and analyzed)	3	23%
	13b	Give reasons for nonparticipation at each stage	0	0%
	13c	Consider use of a flow diagram	0	0%
	14a	Give characteristics of study participants and information regarding exposures and potential confounders	13	100%
	14b	Indicate the number of participants with missing data for each variable of interest	0	0%
Descriptive data	14c	Summarize followup time (eg, average and total amount)	11	85%
Outcome data	15	Report number of outcome events or summary measures with time	8	62%
Main results	16a	Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision	3	23%
	16b	Report category boundaries when continuous variables were categorized	2	15%
	16c	If relevant, consider translating estimates of relative risk into absolute risk for a meaningful time	1	8%
Other analyses	17	Report other analyses done (eg, analyses of subgroups and interactions, and sensitivity analyses)	5	38%
Discussion	18	Summarize key results with reference to study objectives	11	85%
	19	Discuss limitations of the study, taking into account sources of potential bias or imprecision; discuss direction and magnitude of any potential bias	1	8%
	20	Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of analyses, results from similar studies, and other relevant evidence	3	23%
	21	Discuss the generalizability (external validity) of the study results	10	77%
Funding	22	Give the source of funding and the role of the funders for the current study and, if applicable, for the original study on which the current article is based	0	0%