Table 1.

Characteristics of the study population

		N miss	N	n	%
Survey		0	7,769
	spring 2004			1,393	17.93
	autumn 2004			1,260	16.22
	spring 2005			1,343	17.29
	autumn 2005			1,273	16.39
	spring 2006			1,218	15.68
	autumn 2006			1,282	16.50
Socio-economic variables
Age (years)		0	7,769
	18–30			1,146	14.75
	31–40			1,501	19.32
	41–50			1,543	19.86
	51–60			1,241	15.97
	61–70			1,561	20.09
	71–79			777	10.00
Gender		0	7,769
	female			4,508	58.03
	male			3,261	41.97
Per capita income per month (Euro)		505	7,264
	< 600			1,659	22.84
	600–800			1,582	21.78
	800–1,000			1,141	15.71
	1,000–1,300			1,363	18.76
	> 1,300			1,519	20.91
Co-payments		192	7,577
	very difficult			1,765	23.29
	somewhat difficult			2,841	37.50
	not difficult			2,971	39.21
Health related variables
Health awareness (HAW)		38	7,731
	strong			3,854	49.85
	medium			3,360	43.46
	little			517	6.69
Self assessed health (SAH)		36	7,733
	good			2,055	26.57
	medium			3,961	51.22
	poor			1,717	22.20
Chronic disease		0	7,769
	yes			3,817	49.13
	no			3,952	50.87
Maximum co-payment of 1%a		0	7,769
	yes			1,096	14.11
	no			6,673	85.89
Outcome variable due to practice charge		0	7,769
effect 'yes' {	delayed physician visit			2,075	26.71
	avoided physician visit			1,400	18.02
	additional physician visit			1,937	24.93
effect 'no'	none of the above			2,357	30.34

^a accepted by the sickness fund as being chronically sick