Intra-Individual Variability in Self-Reported Use of Non-Steroidal Anti-Inflammatory and Analgesic Medicines Depending on Mode of Data Collection - Observations from the Population Study of Women in Gothenburg, Sweden

Figures & data

Table 1 Wording of the Questions Regarding Medicine Use in the Two Questionnaires

	Self-Administered Questionnaire	Interviewer-Administered Questionnaire
Medicine use	Are you using (daily, weekly or monthly) … tablets with salicylates*? … tablets with NSAIDs**? … other painkillers***? … antimigraine tablets?	Considering any medicine you have been prescribed by a doctor or purchased without a prescription in a pharmacy, what are you using?

Notes: *Examples of products containing acetylsalicylic acid were given. **Examples of products containing naproxen, ibuprofen and diclofenac were given. ***Examples of products containing paracetamol and morphine were given.

Table 2 Distribution of the Study Population’s Age in Relation to Education, General Health, Bodily Pain During the Past 4 Weeks, and Reported Pain Conditions in Previous 3 Months (n=573)

	Age
	38 Years (n = 263)	50 Years (n = 310)	p-value*
Educational level
High school examination or less	68 (26.5%)	122 (39.7%)	0.001
University studies	189 (73.5%)	185 (60.3%)
Bodily pain during the past 4 weeks**
None	73 (27.9%)	74 (24.1%)	0.279
Very mild to moderate	178 (67.9%)	212 (69.1%)
Severe or very severe	11 (4.2%)	21 (6.8%)
Pain that interfered with normal work during the past 4 weeks**
Not at all	146 (55.7%)	160 (52.1%)	0.340
A little bit to moderately	101 (38.5%)	120 (39.1%)
Quite a bit to extremely	15 (15.7%)	27 (8.8%)
Type of pain during the past 3 months***
Headache (incl. migraine)	187 (71.9%)	189 (61.8%)	0.011
Joint pain	50 (19.3%)	113 (36.9%)	<0.001
Back pain	120 (46.2%)	130 (42.3%)	0.363
Pain in legs or knees	50 (19.2%)	93 (30.3%)	0.002

Notes: *Pearson’s chi-square. **From the domain “Pain” in the Short Form (36) Health Survey, self-administered questionnaire filled in at home before the first clinic appointment. ***From the interviewer-administered questionnaire with closed-ended questions. Bold text: Significance at a 5% level.

Table 3 NSAIDs and Analgesics in Current Use According to Data from Self-Administered Vs Interviewer-Administered Questionnaires (n=573)

	Use of Medicines as Reported by Different Modes of Data Collection
Type of medicine (ATC code)	Self-administered questionnaire (closed-ended questions)	Interviewer-administered questionnaire (open-ended questions)
	n (%)	n (%)	Cohen’s Ⱪ	p-value
NSAIDs and analgesics (M01A, N02)	393 (69.3%)	335 (58.5%)	0.27	<0.001
NSAIDs (M01A)	296 (52.4%)	191 (33.3%)	0.36	<0.001
Analgesics (N02)	319 (56.3%)	234 (40.8%)	0.24	<0.001
Opioids (N02A)*	–	13 (2.3%)
Other (N02B)*	–	219 (38.2%)
Salicylates (N02BA)	90 (16.0%)	25 (4.4%)	0.18	<0.001
Paracetamol (N02BE)*	–	203 (35.4%)
Antimigraine preparations (N02C)	42 (7.4%)	12 (2.1%)	0.00	0.835

Notes: *Reported as “other analgesics” in the self-administered questionnaire; separate values not available. Bold text: Significance at a 5% level.

Table 4 Adjusted Odds Ratios (ORs) for the Reported Use of NSAIDs and Analgesics by Different Modes of Data Collection in Relation to Age and Experience of Pain During the Past 4 Weeks (n=573)

		Self-Administered Questionnaire*				Interviewer-Administered Questionnaire**
		n	%	OR	95% CI	n	%	OR	95% CI
Age	38 years (Ref)	191	73.5	1.0		170	64.6	1.0
	50 years	202	65.8	0.6	0.44–0.89	165	53.2	0.6	0.42–0.83
Score on bodily pain (past 4 weeks)***	76–100 (Ref)	193	59.6	1.0		180	55.2	1.0
	51–75	115	77.2	2.5	1.66–3.75	90	60.4	1.3	0.87–1.92
	26–50	60	90.9	4.0	2.15–7.26	43	64.2	1.5	0.87–2.63
	0–25	25	92.6	7.6	2.56–22.63	21	77.8	3.1	1.22–8.02

Notes: *Hosmer-Lemeshow test of model fit: Chi-square: 0.75 (p=0.945). **Hosmer-Lemeshow test of model fit: Chi-square: 0.86 (p=0.930). ***Domain from the Short Form (36) Health Survey, self-administered questionnaire filled in at home before the first clinic appointment. Bold text: Significance at a 5% level.