10. Systolic blood pressure ‐ Studies undertaking multivariable regression analyses to determine the effect of systolic blood pressure on progression to PDR.

Study	Study type	Time years	N at baseline	Adjustment factors	Effect estimate			P value	Comments
					Type	Value	95% CI		Per increase in one year
Type 1 diabetes
WESDR Klein 89	Prospective cohort	4	996	HbA1c, DR severity at baseline, age	OR	1.01	0.99 to 1.03	0.4	Increasing SBP
Janghorbani 2000	Retrospective cohort	5	1349	HbA1c, DM duration	RR	1.61	1.18 to 2.20	< 0.01	> 160mmHg
WESDR  Report XXII	Prospective cohort	25	996	HbA1c, proteinuria, BMI	HR	1.14	1.04 to 1.25	0.01	Per 10 mmHg
Grauslund 2009	Prospective cohort	25	573	HbA1c, DM duration, DR severity at baseline, age, sex, proteinuria, SBP, BMI, smoking, maculopathy	OR	0.91	0.69 to 1.20		Per 10 mmHg
Type 2 diabetes
WESDR Klein 1989	Prospective cohort	4	1370	HbA1c, DR severity at baseline, age				Nonsignificant
Lee 2021	Retrospective cohort	6	2623	HbA1c, DR severity at baseline, age, sex, BMI	HR	1.11		0.11	Per one standard deviation
Lee 1992	Prospective cohort	12	354	DM duration, age, fasting plasma glucose, cholesterol, DM treatment	Regression estimate			0.06	Per unit increase
Type 1 and 2 diabetes
Janghorbani 2000	Retrospective cohort	5	3482	HbA1c, DM duration, proteinuria, type of DM	RR	1.41	1.17 to 1.70	<0.001	> 160mmHg
Keen 2001	Prospective cohort	8	4483	DM duration, age, sex, DBP, cholesterol, comorbidities, BMI, smoking status, insulin treatment, type of DM	OR			Nonsignificant	Per 10 mmHg increase

BMI: body mass index; CI: confidence interval; DBP: diastolic blood pressure; DM: diabetes mellitus; DR: diabetic retinopathy; HbA1c: glycated haemoglobin/haemoglobin A1c; HR: hazard ratio; NPDR: non‐proliferative diabetic retinopathy; OR: odds ratio; PDR: proliferative diabetic retinopathy; RR: risk ratio; SBP: systolic blood pressure; vs: versus