Opting to wear prismatic spectacles was associated with reduced neck pain in dental personnel: a longitudinal cohort study

Table 3 Changes between baseline and follow-up among participants in the questionnaire survey, in frequency of neck/shoulder complaints and perceived exertion. Data is shown for the Intervention group^a and the Reference group, stratified by frequency of complaints at baseline

	Frequency of complaints at baseline
	Twice a month or less			Once a week or more
	Intervention group	Reference group	p-value^b	Intervention group	Reference group	p-value^b
Questionnaire	n = 60	n = 58		n = 110	n = 70
Frequency of complaints
Higher	7 (12)	18 (31)		5 (5)	8 (11)
Unchanged	42 (70)	29 (50)		49 (45)	28 (40)
Lower	11 (18)	11 (19)	0.112	56 (51)	34 (49)	0.392
Perceived exertion^c,d
Worse	19 (33)	22 (41)		19 (17)	22 (32)
Unchanged	10 (17)	17 (31)		27 (25)	15 (22)
Better	29 (50)	15 (28)	0.083	64 (58)	32 (46)	0.040

^a66 participants who were given prismatic glasses but reported that they did not use them on a regular basis, were excluded
^bLinear-by-Linear Association
^cTwice a month or less; 2 subjects missing in the intervention group and 4 missing in the reference group
^dOnce a week or more; 1 subject missing in the reference group
Values presented are number (%)

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