Table 3.

Predictors of the three skin ageing measures in proportional odds regression models adjusted for age, sex, highest educational level attained and melanoma status

	Wrinkles			Vascularity			Pigmentation
	n	OR (95% CI)	P-valuea	n	OR (95% CI)	P-valuea	n	OR (95% CI)	P-valuea
Age at examinationb	1337	2·50 (2·26–2·76)	< 0·001	1332	1·35 (1·23–1·48)	< 0·001	1332	1·12 (1·03–1·23)	0·01
Sex (male vs. female)b	1337	1·56 (1·28–1·89)	< 0·001	1332	7·52 (5·99–9·45)	< 0·001	1332	1·43 (1·17–1·74)	0·001
Highest educational levelb	1317			1312			1312
Primary/secondary school	464	1		460	1		459	1
Sixth form/vocational training	559	0·71 (0·57–0·88)	0·002	557	0·84 (0·67–1·05)	0·13	559	1·29 (1·03–1·62)	0·03
University/postgraduate	294	0·55 (0·42–0·72)	< 0·001	295	0·92 (0·71–1·20)	0·55	294	1·57 (1·20–2·05)	0·001
Sun-sensitive phenotype (yes vs. no)	1298	0·83 (0·67–1·01)	0·07	1292	1·05 (0·86–1·29)	0·63	1292	0·84 (0·69–1·03)	0·10
MC1R genotype	1110			1106			1104
Wild-type (wt)	223	1		223	1		223	1
r/wt	256	1·12 (0·81–1·55)	0·48	254	1·39 (0·99–1·94)	0·05	255	0·77 (0·56–1·07)	0·13
r/r	95	1·08 (0·69–1·68)	0·75	94	1·25 (0·80–1·96)	0·33	94	0·56 (0·36–0·86)	0·01
R/wt	263	1·01 (0·73–1·40)	0·96	261	1·09 (0·78–1·52)	0·60	260	0·55 (0·39–0·76)	< 0·001
R/r	181	1·21 (0·85–1·74)	0·29	180	1·45 (1·01–2·10)	0·05	179	0·58 (0·41–0·83)	0·003
R/R	92	0·80 (0·51–1·25)	0·33	94	1·73 (1·10–2·72)	0·02	93	1·15 (0·72–1·83)	0·55
MC1R genotype – grouped	1110			1106			1104
Wild-type	223	1		223	1		223	1
‘r’ without ‘R’	351	1·11 (0·82–1·51)	0·50	348	1·35 (0·99–1·85)	0·06	349	0·71 (0·52–0·96)	0·03
‘R’	536	1·03 (0·78–1·38)	0·82	535	1·29 (0·97–1·73)	0·08	532	0·63 (0·47–0·83)	0·001
BMI	1303	0·98 (0·86–1·13)	0·82	1298	1·23 (1·07–1·41)	0·003	1298	1·01 (0·88–1·15)	0·93
Smoking (ever vs. never)c	758	0·97 (0·74–1·27)	0·81	758	1·16 (0·89–1·52)	0·28	756	0·87 (0·66–1·14)	0·30
Pack-yearsc	729	1·08 (0·91–1·27)	0·37	727	1·21 (1·02–1·43)	0·03	726	0·88 (0·74–1·04)	0·13
Average alcohol intakec	753	0·98 (0·86–1·11)	0·71	754	0·91 (0·80–1·04)	0·16	752	0·90 (0·79–1·02)	0·11
Average daily sun exposure	1256	0·98 (0·89–1·08)	0·70	1252	1·12 (1·02–1·24)	0·02	1252	1·06 (0·97–1·17)	0·20
Average weekday sun exposure – overall	1257	0·96 (0·88–1·06)	0·44	1252	1·12 (1·02–1·23)	0·02	1252	1·09 (0·99–1·19)	0·07
Average weekday sun exposure – cooler months	1258	0·95 (0·87–1·05)	0·31	1253	1·11 (1·01–1·22)	0·04	1253	1·06 (0·97–1·16)	0·22
Average weekday sun exposure – warmer months	1262	1·00 (0·92–1·10)	0·94	1257	1·09 (0·99–1·20)	0·06	1257	1·11 (1·01–1·22)	0·03
Average weekend sun exposure – overall	1269	0·99 (0·90–1·10)	0·88	1265	1·05 (0·95–1·16)	0·35	1265	1·03 (0·94–1·14)	0·50
Average weekend sun exposure – cooler months	1272	0·95 (0·86–1·05)	0·30	1268	1·01 (0·91–1·12)	0·88	1268	1·03 (0·93–1·13)	0·62
Average weekend sun exposure – warmer months	1271	1·06 (0·97–1·17)	0·22	1267	1·06 (0·96–1·17)	0·22	1267	1·04 (0·94–1·14)	0·46
Average holiday sun exposure – overall	1270	1·04 (0·95–1·14)	0·38	1266	1·03 (0·94–1·13)	0·55	1266	1·04 (0·95–1·14)	0·39
Average holiday sun exposure – 10:00–14:00 h	1265	1·01 (0·92–1·11)	0·78	1261	1·06 (0·96–1·17)	0·23	1261	1·05 (0·96–1·15)	0·32
Average holiday sun exposure – below 45° N latitude	1270	1·02 (0·92–1·12)	0·74	1266	1·02 (0·93–1·12)	0·70	1266	1·08 (0·98–1·18)	0·13
Average holiday sun exposure – below 45° N latitude (10:00–14:00 h)	1265	1·00 (0·91–1·10)	0·99	1261	1·02 (0·93–1·12)	0·66	1261	1·09 (0·99–1·20)	0·06
Sunburn – no. before age 20 years	1272	0·87 (0·75–1·02)	0·08	1267	1·04 (0·90–1·23)	0·56	1267	0·90 (0·77–1·05)	0·19
Sunburn – no. at or after age 20 years	1257	1·07 (0·92–1·25)	0·36	1252	1·06 (0·92–1·25)	0·40	1252	0·93 (0·80–1·09)	0·37
Sunburn – average no. in life	1262	0·92 (0·81–1·04)	0·16	1257	1·05 (0·93–1·19)	0·42	1257	0·90 (0·80–1·02)	0·11
Sunbed – ever vs. never	1296	0·99 (0·80–1·24)	0·97	1291	0·96 (0·77–1·19)	0·70	1291	0·88 (0·71–1·10)	0·26
Sunbed – no. of sessions in life	1274	0·94 (0·82–1·08)	0·37	1269	0·97 (0·84–1·12)	0·66	1269	0·93 (0·81–1·07)	0·30
Sunscreen – used to avoid sunburn	1317	0·90 (0·79–1·02)	0·11	1312	0·98 (0·87–1·12)	0·81	1312	0·90 (0·79–1·03)	0·12
Sunscreen – used to stay in the sun longer	1317	0·93 (0·82–1·06)	0·29	1312	1·00 (0·88–1·14)	0·98	1312	0·86 (0·76–0·98)	0·03
Sunscreen – SPF level	1317	0·84 (0·74–0·96)	0·01	1312	0·99 (0·87–1·14)	0·97	1312	0·93 (0·82–1·06)	0·29

Findings significant at the 5% level are highlighted in bold. n, number of observations in each model; OR, odds ratio; CI, confidence interval; BMI, body mass index; SPF, sun-protection factor.

^aP-values for trend are presented, as displayed in Table 2, except for highest educational level and MC1R genotypes. Sun-exposure measures were analysed as a trend across quartiles.

^bAdjusted only for melanoma status.

^cAdjusted only for age, sex and education.