Table 1

Comparison of the baseline variables among the respondents (n=180) and non-respondents (n=52) of the follow up survey

	Respondents		Non-respondents
	n	%	n	%	p value
Work related variables
VDU working time					0.54
<50%	122	70	34	71
⩾50%	52	30	14	29
Physical work environment					0.08
Mean score >3	123	70	42	81
Mean score ⩽3	53	30	10	19
Ergonomics of workstation					0.34
Mean score >3	127	72	39	76
Mean score ⩽3	49	28	12	24
Distance of the screen					0.42
Good (50–70 cm)	106	69	29	66
Poor (<50 cm or >70 cm)	48	31	15	34
Height of the screen					0.18
Good (⩾10 cm)	102	68	33	77
Poor (<10 cm)	48	32	10	23
Distance of the keyboard					0.19
Good (⩾15 cm)	70	49	14	39
Poor (<15 cm)	73	51	22	61
Deviance of the keyboard					0.07
Good (0±2 cm)	73	51	24	67
Poor (> ±2 cm)	70	49	12	33
Distance of the mouse					0.19
Good (⩾15 cm)	46	51	10	38
Poor (<15 cm)	45	49	16	62
Deviance of the mouse					0.22
Good (0±30 cm)	38	42	8	31
Poor (> ±30 cm)	53	58	18	69
Breaks during work					0.59
Fully enough	66	63	17	63
Rather enough/rather little/much too little	39	37	10	37
Influence on work load					0.45
Somewhat/rather/very much	93	52	26	50
Very little/rather little	85	48	26	50
Individual variables
Sex					0.29
Female	80	44	26	50
Male	100	56	26	50
Age					0.04
25–43	58	32	11	22
44–51	59	33	12	23
52–61	62	35	28	55
Smoking					0.22
Never smoker	97	55	25	48
Current/ex-smoker	78	45	27	52
Frequency of physical exercise (times/week)					0.34
⩽1	54	30	18	35
⩾2	124	70	34	65
Health status					0.27
Very good/rather good	120	68	31	62
Average/rather poor/very poor	57	32	19	38
Mental stress					0.02
None/little	88	50	34	68
Some/fairly much/much	89	50	16	32
Mental strain					0.29
Never/rather seldom	99	56	31	62
Sometimes/rather often/continually	77	44	19	38
Depression					0.37
Never/rather seldom	117	66	35	70
Sometimes/rather often/continually	60	34	15	30
Job satisfaction					0.55
Very satisfied/rather satisfied	135	76	38	76
Neutral/rather/very dissatisfied	42	24	12	24
Time used for domestic activities (hours/day)					0.28
<1	48	27	17	33
⩾1	128	73	35	67
Time used for hobbies (hours/day)					0.56
<1	139	79	41	79
⩾1	37	21	11	21