Summary of findings for the main comparison. First‐line allogeneic hematopoietic stem cell transplantation of HLA‐matched sibling donors compared with first‐line ciclosporin and/or antithymocyte or antilymphocyte globulin for acquired severe aplastic anemia.

First‐line allogeneic hematopoietic stem cell transplantation of HLA‐matched sibling donors compared with first‐line ciclosporin and/or antithymocyte or antilymphocyte globulin for acquired severe aplastic anemia
Patient or population: patients with acquired SAA Settings: hospital Intervention: first‐line allogeneic hematopoietic stem cell transplantation of HLA‐matched sibling donors (MSD‐HSCT) Comparison: first‐line ciclosporin and/or antithymocyte or antilymphocyte globulin (IST)
Outcomes	Illustrative comparative risks* (95% CI)		Relative effect (95% CI)	No of participants (studies)	Quality of the evidence (GRADE)	Comments
	Assumed risk	Corresponding risk
	First‐line ciclosporin and/or antithymocyte or antilymphocyte globulin (IST)	First‐line allogeneic hematopoietic stem cell transplantation of HLA‐matched sibling donors (MSD‐HSCT)
Overall mortality Follow‐up: 2 years	Moderate1		HR 0.95 (0.45 to 1.91)	203 (3 studies)	⊕⊕⊝⊝ low2,3
	31 per 100	30 per 100 (15 to 51)
Treatment‐related mortality Follow‐up: not reported	See comment	See comment	Not estimable	54 (2 studies4)	⊕⊝⊝⊝ very low4	Case series; 15 of 54 of the MSD‐HSCT group affected
Health‐related quality of life	See comment	See comment	Not estimable	0 (0)	See comment	No studies identified
Graft failure Follow‐up: not reported	See comment	See comment	Not estimable	54 (2 studies4)	⊕⊝⊝⊝ very low4	Case series; 4 of 54 of the MSD‐HSCT group affected
No response to IST Follow‐up: not reported	See comment	See comment	Not estimable	35 (2 studies4)	⊕⊝⊝⊝ very low4	Case series; 16 of 35 of the IST group affected
Graft‐versus‐host disease Follow‐up: not reported	See comment	See comment	Not estimable	52 (2 studies4)	⊕⊝⊝⊝ very low4	Case series; 22 of 52 of the MSD‐HSCT group affected
Secondary clonal disease or malignancies Follow‐up: not reported	Moderate1		Peto OR 0.54 (0.07 to 4)	170 (2 studies)	⊕⊕⊝⊝ low2,3
	2 per 100	1 per 100 (0 to 10)
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; HR: hazard ratio; IST: immunosuppressive therapy; MSD‐HSCT: first‐line allogeneic hematopoietic stem cell transplantation from HLA‐matched (identical) sibling donor; OR: odds ratio
GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate.

¹Median control group risk across studies.
 ²'Mendelian randomization'.
 ³Wide confidence interval.
 ⁴Case series.