Table 1.

Uncoded and coded CKD Read codes among an adult population with biochemical CKD stage 3–5 (n = 9325), by selected clinical characteristics

Variable	Total, N	Uncoded CKD		Coded CKD		P-value
		n	%a	n	%a
CKD stage ≥3	9325	5086	54.5	4239	45.5
Sex
Female	5312	2858	53.8	2454	46.2
Male	4013	2228	55.5	1785	44.5	0.10
Age group, years
<50	1167	956	81.9	211	18.1	<0.001
50–59	1464	1077	73.6	387	26.4
60–69	1574	942	59.8	632	40.2
70–79	2502	1130	45.2	1372	54.8
80–89	2117	783	37.0	1334	63.0
≥90	501	198	39.5	303	60.5
Ethnicity
White	3847	1758	45.7	2089	54.3	<0.001
Black African	1440	984	68.3	456	31.7
Black Caribbean	2196	1297	59.1	899	40.9
South Asian	540	260	48.1	280	51.9
Chinese	62	30	48.4	32	51.6
Other ethnicity	171	98	57.3	73	42.7
Non-stated	206	129	62.6	77	37.4
Missing	863	530	61.4	333	38.6
IMD quintile
1 (least deprived)	2252	1193	53.0	1059	47.0	0.42
2	2000	1102	55.1	898	44.9
3	1600	886	55.4	714	44.6
4	1741	968	55.6	773	44.4
5 (most deprived)	1726	932	54.0	794	46.0
Missing	6	5	83.3	1	16.7
Comorbid conditions
Previous stroke	678	293	43.2	385	56.8	<0.001
CHD	1389	500	36.0	889	64.0	<0.001
Hypertension	6318	2873	45.5	3445	54.5	<0.001
Type 2 diabetes	2537	1079	42.5	1458	57.5	<0.001
Heart failure	751	243	32.4	508	67.6	<0.001
Serious mental illness	431	225	52.2	206	47.8	0.32

^aPercentages are calculated using the total figure for each variable as denominator, unless otherwise stated. CHD = coronary heart disease. CKD = chronic kidney disease. IMD = Index of Multiple Deprivation.