Table 2

Predictors and their primary studies with confirmation and replication status

Group	No	Predictors	Model mentioning predictor	Status
Ocular features	1	Retinopathy level/DR grade	Lagani et al14	C,48 R70
	2	Proliferative DR	Hippisley-Cox and Coupland11*	C,48 R71
	3	Maculopathy	Hippisley-Cox et al11*	C,48 R71
	4	Visual acuity score	Lagani et al14	C51
Sociodemographics	5	Age	Multiple studies11 42 57	C,43 R55
	6	Race	Harris et al 11 63 (L)	E3 63 Lack of evidence
	7	Gender	Harris et al63	C,62 R43
	8	Social deprivation score	Hippisley-Cox and Coupland11*	C,59 R72
Diabetes characteristics	9	Type of DM	Icelandic model73*	C74
	10	Age at diagnosis	UKPDS OM275*	C,76 R55
	11	Duration of DM	Icelandic model73	C,48 R70
Biochemical parameters	12	HbA1c	UKPDS OM177	C,51 R49
	13	eGFR	UKPDS OM275 Stratton et al,60 ISDR35*	C,78 R38 C,79 R55
	14	Total serum cholesterol	Soedamah-Muthu et al57 UKPDS OM177	C,39 R55 C,40 R53
Physical examination	15	DBP	Icelandic model73*	C74
Physical examination	16	SBP	UKPDS OM277*	C,76 R55
Comorbidities	17	Hypertension	Harris et al63	C39
	18	Dyslipidaemia	Harris et al63	C,79 R80
	29	Psychiatric illness	Lagani et al14 (L)*	Absence of evidence
Diabetic complications	20	Chronic renal disease	*Hippisley-Cox and Coupland11	C81
	21	Diabetic nephropathy	Harris et al63	C,62 R37
	22	Diabetic neuropathy	Harris et al63 (L)*	Absence of evidence
Diabetes treatment	23	Statin	Harris et al63	C,82 R80
Diabetes treatment	24	Insulin	Harris et al63*	C,83 R50
Lifestyle	25	Smoking	McEwan et al61 (L)	C,43 44 Absence of evidence
	26	BMI	McEwan et al and others14 42 61 (L)*	C,41 Absence of evidence
	27	Exercise/physical activity	Tanaka13 (L)	Absence of evidence
New from NGT	28	Only eye situation	NA (L)	Absence of evidence
	29	Early worsening	NA	C,45 R84
	30	Frequent DNA	NA (L)	C47 Lack of evidence
	31	Pregnancy	NA	C,46 R52
	32	Diet	NA (L)	Absence of evidence
	33	Preproliferative DR	NA	C,48 R85
	34	Chronic infection	NA (L)	Absence of evidence
	35	Comorbidities	NA (L)	Absence of evidence

*Modelling study did not clearly identify the primary study for the predictor. Details in text.
BMI, body mass index; C, confirmation; DBP, diastolic blood pressure; DM, diabetes mellitus; DNA, did not attend; DR, diabetic retinopathy; E, exploration; eGFR, estimated glomerular filtration rate; HbA1c, glycated haemoglobin; ISDR, Individualised Screening for Diabetic Retinopathy; L, lacking evidence; NA, not applicable; R, replication; SBP, systolic blood pressure ; UKPDS, United Kingdom prospective Diabetes Study.