Table 4.

Percentages of missing data in the general practice total population and subgroups in the Extramural Leiden University Medical Center Academic Network

			Age (years) b
Characteristic	Overall GP	Diabetes a	<18	18–65	≥65
N	734 519	49 689	238 282	422 807	73 430
Demographics (%)c
Sex	0	0	0	0	0
Age	0	0	0	0	0
Person-years	0	0	0	0	0
Disposable household income	4.5	1.6	6.7	3.5	3.2
Education	34.4	64.4	4.4	40.9	94.0
Country of origin	0	0	0	0	0
Municipality	0	0	0	0	0
Laboratory findings and measurements (%)c
ALAT	56.0	16.7	78.4	47.6	32.1
Creatinine	49.7	6.4	76.0	39.6	23.0
Haemoglobin	43.1	11.4	62.1	35.7	24.1
Sedimentation rate	48.6	16.4	68.8	41.0	26.7
Total cholesterol	64.3	9.8	95.7	51.7	34.9
TSH	51.6	20.3	72.3	43.2	32.9
Smoking status	69.3	17.1	91.6	60.0	50.2
Systolic blood pressure	54.5	7.6	81.7	44.1	26.2
Weight	64.9	12.3	75.0	62.6	44.6

ALAT, alanine aminotransferase; GP, general practice; TSH, thyroid-stimulating hormone.

^aPopulation with a type 2 diabetes diagnosis before or during follow-up.

^bAge when entering the data infrastructure (entry date before 2007; date was capped at 1 January 2007).

^cPercentage of missing data.