2.7.4 Serum Creatinine and Glomerular Filtration Rate [GFR] Data

Table 22 provides data on Serum Creatinine for individuals, as the percent of individuals in the (arbitrary) categories of: [below 120], [120-500] or [over 500] micromols per litre. See Frequency Tables for n= and range data.

Table 22 – Percent (%) Serum Creatinine

Serum Creatinine	[All n]	All Sites n=3767	Adult Forms Only n=3767	Paediatric Forms Only n=0
< 120 µmol / L	3204		85.1
120 - 500 µmol / L	527		14.0
> 500 µmol / L	36		1.0

See Tables on Pages 139-140 of Appendix 5 for Serum Creatinine Data. The Graphs show the spread/comparison of site’s results ranked in order for totals and broken down by Age. The pages are All sites data[A], which in 2011 is equivalent to Adult Forms data .

From 2002 onwards, we have undertaken Glomerular Filtration Rate [GFR] calculations. Rather than using the Cockcroft-Gault equation [which tends to over estimate low and under estimate hyper filtration], we have used the MDRD [Modified Diet in Renal Disease] Study¹⁵, 4 - variable formula [see below #] - (Serum Creatinine; Age; Height and Weight – with loading for female & ATSI). We have calculated GFR for all with appropriate data aged ≥20.
The results are shown in Tables 25 – [a] All patients [b] Type 1 and [c] Type 2.

The data have been converted to Low, Normal and High GFR based on sex and decade-specific age ranges as reported in the MDRD Study paper¹⁵ [which are based on their findings in non-diabetic individuals]. These compensate for the approximate 10 ml/min/1.73 sq.m GFR decline per decade over 40 years.



Table 25[d] provides data on the degree / severity of reduced eGFR [with retrospective calculations for 2004, 2006 and 2009 data – {not previously undertaken} – for comparison].

In addition in Table 25[d], for 2011 data only – where data are available, we have assessed the individuals stated to be on Metformin Therapy who have a calculated / estimated GFR of <=30, being n=16. This represents 0.6% of those patients stated to be on Metformin therapy.

Table 25[a] – GFR ^# (ml/min/1.73 sq.m) [All Patients]

Sex	Age	N	Low	Low %	Normal	Normal %	High	High %
Male	20-29	138	61	44.2%	66	47.8%	1	0.7%
	30-39	160	46	28.8%	96	60.0%	2	1.3%
	40-49	263	93	35.4%	139	52.9%	2	0.8%
	50-59	487	137	28.1%	302	62.0%	4	0.8%
	60-69	716	233	32.5%	403	56.3%	14	2.0%
	70-79	477	141	29.6%	262	54.9%	21	4.4%
	80+	147	46	31.3%	72	49.0%	16	10.9%
	Total	2388	757	31.7%	1340	56.1%	60	2.5%
Female	20-29	185	73	39.5%	93	50.3%	6	3.2%
	30-39	193	71	36.8%	87	54.1%	14	7.3%
	40-49	231	57	24.7%	139	60.2%	14	6.1%
	50-59	393	99	25.2%	236	60.1%	22	5.6%
	60-69	501	145	28.9%	264	52.7%	41	8.2%
	70-79	408	112	27.5%	203	49.8%	56	13.7%
	80+	140	33	23.6%	72	51.4%	22	15.7%
	Total	2051	590	28.8%	1094	53.3%	175	8.5%
Total		4439	1347	30.3%	2434	54.8%	235	5.3%

Table 25[b] – GFR ^# (ml/min/1.73 sq.m) [Type 1]

Sex	Age	N	Low	Low %	Normal	Normal %	High	High %
Male	20-29	126	57	45.2%	59	46.8%	1	0.8%
	30-39	100	25	25.0%	62	62.0%	1	1.0%
	40-49	76	21	27.6%	48	63.2%	0	0.0%
	50-59	92	25	27.2%	53	57.6%	1	1.1%
	60-69	39	10	25.6%	25	64.1%	1	2.6%
	70-79	26	6	23.1%	18	69.2%	2	7.7%
	80+	8	0	0.0%	7	87.5%	1	12.5%
	Total	467	144	30.8%	272	58.2%	7	1.5%
Female	20-29	133	47	35.3%	75	56.4%	2	1.5%
	30-39	94	26	27.7%	53	56.4%	2	2.1%
	40-49	92	22	23.9%	53	57.6%	7	7.6%
	50-59	65	17	26.2%	34	52.3%	3	4.6%
	60-69	45	14	31.1%	22	48.9%	5	11.1%
	70-79	14	3	21.4%	6	42.9%	3	24.4%
	80+	8	3	37.5%	3	37.5%	0	0.0%
	Total	451	132	29.3%	246	54.5%	22	4.9%
Total		918	276	30.1%	518	56.4%	29	3.2%

Table 25[c] – GFR ^# (ml/min/1.73 sq.m) [Type 2]

Sex	Age	N	Low	Low %	Normal	Normal %	High	High %
Male	20-29	11	4	36.4%	6	54.5%	0	0.0%
	30-39	53	17	32.1%	31	58.5%	1	1.9%
	40-49	117	70	39.5%	85	48.0%	2	1.1%
	50-59	378	105	29.8%	239	63.2%	3	0.8%
	60-69	652	215	33.0%	367	56.3%	13	2.0%
	70-79	442	134	30.3%	238	53.8%	19	4.3%
	80+	137	46	33.6%	64	46.7%	15	10.9%
	Total	1850	591	31.9%	1030	55.7%	53	2.9%
Female	20-29	20	6	30.0%	12	60.0%	0	0.0%
	30-39	40	14	35.0%	17	42.5%	4	10.0%
	40-49	123	28	22.8%	81	65.9%	5	4.1%
	50-59	316	79	25.0%	194	61.4%	19	6.0%
	60-69	444	128	28.8%	236	53.2%	36	8.1%
	70-79	385	105	27.3%	193194	50.1%	52	13.5%
	80+	131	30	22.9%	69	52.7%	21	16.0%
	Total	1459	390	26.7%	802	55.0%	137	9.4%
Total		3309	981	29.6%	1832	55.4%	190	5.7%

Table 25[d] – GFR ^# (ml/min/1.73 sq.m)

GFR	2004		2006		2009		2011
	n	%	n	%	n	%	n	%
>60	1344	44.7	851	53.4	2381	40.7	2238	50.4
>45 and ?60	345	11.5	235	14.8	487	8.3	495	11.2
>30 and ?45	169	5.6	139	8.7	292	5.0	324	7.3
≤30	101	3.4	80	5.0	162	2.8	181	4.1
Missing	1049	34.9	288	18.1	2525	43.2	1201	27.1
≤30 and Meformin = Yes	Not Collected		Not Collected		32	1.1	16	0.6
Total	3008		1593		5847		4439

In 2011, having collected eGFR for the first time, we undertook the same analyses as shown in Table 25[d], and the results appear in Table 25[e].

Table 25[e] – eGFR

GFR	2011
	n	%
>60	2781	60.5
>45 and ?60	489	10.6
>30 and ?45	289	6.3
≤30	207	4.5
Missing	832	18.1
≤30 and Meformin = Yes	16	0.7
Total	4598

These analyses shows more available eGFR results, with more individuals reportedly normal (>60) than in the MDRD calculations in Table 25[d] (60.5% versus 50.4%). The other results are similar with 4.5% having an eGFR ≤30 (versus 4.1% in Table 25[d]).

# GFR (mL/min/1.73sq.m) = GFR x 1.73 / SA
GFR (mL/min) = 186.3 x Serum Creatinine^-1.154 x Age^-0.203 x 1.212 (if ATSI) x 0.742 (if female)
SA = 0.007184 x height^0.725 x weight^0.425