Characteristics of the samples
Of the 1,198 HaBIDS participants included in this study, 748 were female (62%) and 450 were male (38%). The median age was 47 years (interquartile range [IQR] 35–57 years); 36 participants (3%) were below the age of 20 years and 213 participants (18%) were over 60 years old. SBG participants had a median age of 47 years (IQR 32–58), while it was 34 years (IQR 24–52) for Natsal participants and 28 years (IQR 21–36) for NSFG participants. Further information on the study populations can be found in Table 1.
Current partnership and age at sexual debut
There were no relevant differences in sexual contact patterns between HaBIDS participants using a paper-based questionnaire and those using an online questionnaire when taking age, sex, and education into account (Supplementary Table S1). At the time of data collection, 83% of the participants had a sexual partner and 60% of those thought that this sexual relationship will also continue for at least three months. Thirty participants (2.5%; 20 men, 10 women; median age 18, IQR 17–26) reported that they have never had a sexual contact in their lifetime.
Men were older at their sexual debut than women in HaBIDS (median ages 18 years vs 17 years; Table 2, Fig. 1) as well as in the other studies. Participants with a university qualification or university degree were generally older at sexual debut when compared to those without a university qualification (Fig. 1). Women reported more often a sexual relationship with older opposite sex partners while men reported frequently to be engaged in sexual relationships with younger opposite sex partners (Fig. 2).
Table 2
Demographic and sexual behaviour of the HaBIDS participants (IQR; interquartile range)
|
Men (N = 450)
|
Women (N = 748)
|
Total (N = 1,198)
|
|
N
|
Median [IQR]
|
N
|
Median [IQR]
|
N
|
Median [IQR]
|
Age of participants (in years)
|
449
|
49 [36–59]
|
748
|
46 [35–55]
|
1197
|
47 [35–57]
|
Age of participants sexual debut (in years)
|
417
|
18 [17–20]
|
726
|
17 [16–19]
|
1143
|
18 [16–19]
|
|
N
|
%
|
N
|
%
|
N
|
%
|
Marital status
|
Married
|
263
|
60
|
445
|
61
|
708
|
61
|
Single
|
138
|
32
|
194
|
27
|
332
|
28
|
Divorced
|
32
|
7
|
68
|
9
|
100
|
8
|
Widowed
|
5
|
1
|
25
|
3
|
30
|
3
|
Highest completed educational level
|
University degree
|
213
|
48
|
274
|
37
|
487
|
42
|
University entrance qualification
|
123
|
28
|
195
|
27
|
318
|
27
|
Lower secondary education or
Apprenticeship
|
92
|
21
|
253
|
35
|
345
|
29
|
Still student
|
11
|
3
|
10
|
1
|
21
|
2
|
Do you currently have a sexual partner?
|
Yes
|
361
|
85
|
594
|
82
|
955
|
83
|
No
|
64
|
15
|
134
|
18
|
198
|
17
|
Do you think this sexual relationship will continue in 3 months?
|
Yes
|
245
|
97
|
328
|
99
|
573
|
97
|
No
|
3
|
1
|
0
|
0
|
3
|
1
|
I don't know
|
6
|
2
|
3
|
1
|
9
|
2
|
Did your partner have sexual intercourse with other people in the last 12 months?
|
Yes (I know that exactly)
|
12
|
3
|
20
|
3
|
32
|
3
|
Yes (I suppose, but I'm not sure)
|
6
|
2
|
11
|
2
|
17
|
2
|
Yes
|
9
|
2
|
15
|
2
|
24
|
2
|
No
|
323
|
80
|
580
|
85
|
903
|
83
|
I do not know
|
54
|
13
|
55
|
8
|
109
|
10
|
Do you know how many sexual partners your partner had in his/her life in total excluding yourself?
|
Yes, I can give an estimate
|
139
|
36
|
258
|
40
|
397
|
39
|
I do not know
|
245
|
64
|
388
|
60
|
633
|
61
|
How often did your partner use condoms in the past partnerships in his/her life?
|
Always (every intercourse)
|
28
|
7
|
41
|
6
|
69
|
7
|
Sometimes
|
54
|
14
|
160
|
25
|
214
|
21
|
Never
|
30
|
8
|
50
|
8
|
80
|
8
|
I do not know
|
268
|
71
|
396
|
61
|
664
|
64
|
In the last 12 months, how often did you use condoms with your last or current partners?
|
Always (every intercourse)
|
46
|
12
|
71
|
12
|
117
|
12
|
Sometimes
|
55
|
15
|
93
|
15
|
148
|
15
|
Never
|
271
|
73
|
451
|
73
|
722
|
73
|
In the last 12 months, how often did you use condoms with your penultimate partners?
|
Always (every intercourse)
|
16
|
30
|
24
|
33
|
40
|
31
|
Sometimes
|
8
|
15
|
17
|
23
|
25
|
20
|
Never
|
30
|
55
|
32
|
44
|
62
|
49
|
In the last 12 months, how often did you use condoms with your pre - penultimate partners?
|
Always (every intercourse)
|
14
|
36
|
11
|
34
|
25
|
35
|
Sometimes
|
8
|
20
|
5
|
16
|
13
|
18
|
Never
|
17
|
44
|
16
|
50
|
33
|
47
|
Lifetime opposite-sex partners
In HaBIDS, men and women had a median of 4 (IQR 2–8, and 2–7, respectively) lifetime opposite-sex sexual partners. In the group of 15 to 19 years old participants, 17 participants (46%) reported to have never had an opposite-sex sexual partner; this proportion decreased strongly for older age groups. Forty-three percent of women and 13% of men reported to have had just a single partner in their entire life. Men had lower numbers of lifetime opposite-sex sexual partners in the younger age groups, and higher numbers in older age groups compared to women (Fig. 3a). Apart from the younger age groups (below 25 years for women and 30 years for men), the proportions of both men and women with a given number of lifetime partners were stable across age.
The number of reported lifetime partners was highest in Natsal followed by NSFG and both German studies (Fig. 4a, left panel, Table 3). The difference in lifetime partners can be linked to differences in the number of partners in younger age groups (14–24 years), while in the older age groups the age-related increase in the number of partners was similar. Consequently, the acquisition of new partners (partners in the last 12 months) differed more in younger age groups across countries (Fig. 4a, right panel). These patterns were generally similar in men and women, although absolute numbers of partners were consistently higher in men. The higher acquisition rate of new partners was not evenly distributed across all participants but caused by a higher proportion of persons in the groups with the highest partner changes (10–19, 20–29, 30 or more) in Natsal and, to a lesser extent, in NSFG (Fig. 4c). Those who reported more lifetime sexual partners had also more sexual partners in the last 12 months, supporting individual stability of behaviour as used in the concept of stable sexual activity groups (Fig. 4b).
Table 3: Comparison of the number of sexual partners between studies adjusted for age and sex. HaBIDS serves as the reference study.
IRR (95% CI; negative binomial regression)
|
SBG
|
NSFG
|
Natsal
|
Lifetime opposite-sex partners
|
1.16 (1.06, 1.27)
|
1.53 (1.42, 1.64)
|
1.76 (1.63, 1.89)
|
Opposite-sex partners in the last 12 months
|
-
|
0.94 (0.88, 1.01)
|
1.04 (0.97, 1.11)
|
New opposite-sex partners in the last 12 months
|
-
|
-
|
1.36 (1.14, 1.62)
|
Lifetime same-sex partners
|
1.32 (0.87, 1.98)
|
0.81 (0.57, 1.13)
|
1.16 (0.81, 1.60)
|
Lifetime same-sex partners (at least one same-sex partner)
|
1.70 (1.30-2.22)
|
1.02 (0.82-1.26)
|
1.91 (1.53-2.37)
|
Same-sex partners in the last 12 months
|
-
|
0.61 (0.43, 0.87)
|
0.90 (0.63, 1.29)
|
New same-sex partners in the last 12 months
|
|
-
|
1.38 (0.73, 2.54)
|
Both-sex sexual partners in the entire life
|
2.31 (1.83, 2.92)
|
2.01 (1.67, 2.40)
|
2.81 (2.33, 3.37)
|
Both-sex sexual partners in the last 12 months
|
-
|
0.86 (0.69, 1.06)
|
1.12 (0.90, 1.39)
|
New sexual partners (both-sex) in the last 12 months
|
-
|
|
1.66 (1.00, 2.67)
|
Note: Opposite/same/both-sex partners in the last 12 months are based on participants who had at least one lifetime opposite/same/both-sex sexual partner. New opposite/same/both-sex sexual partners in the last 12 months are based on participants who had at least one opposite/same/both-sex sexual partner in the last 12 months.
CI, confidence interval; IRR, incidence rate ratio; OR, odds ratio
Opposite-sex partners in the last 12 months
Among HaBIDS participants who had at least one lifetime opposite-sex sexual partner, 14% reported to have had no opposite-sex sexual partner in the last 12 months, while 79% reported one and 7% reported two or more opposite-sex sexual partners in the last 12 months. In the 15 to 19 years old HaBIDS participants, among those with at least one lifetime opposite-sex partner, all women had at least one opposite-sex partner, whereas 25% of men had no opposite-sex sexual partner in the last 12 months (Fig. 3b). While there was no evidence for overall differences between HaBIDS, NSFG (IRR 0.94, 95%CI 0.88–1.01) and Natsal participants (IRR 1.04, 95%CI 0.97–1.11) (Table 3, Supplementary Table S3, Figure S4b), Natsal participants in the age group 15 to 24 years showed a higher number of opposite-sex sexual partner in the last 12 months (IRR 1.29, 95%CI 1.03–1.63) consistent with the analysis on lifetime partners. This was not true for NSFG (IRR 1.06, 95%CI 0.85–1.33) participants.
New opposite-sex partners in the last 12 months
Of those participants in HaBIDS with at least one opposite-sex sexual partner in the last 12 months, only 19% reported one or more new opposite-sex sexual partners in the last 12 months. The highest proportion of participants who reported a new opposite-sex sexual partner occurred in the age group 15 to 19 years (88%) (Fig. 3c). Natsal reported a slightly higher number of new opposite-sex sexual partners (IRR 1.36, 95%CI 1.14–1.62) among those who had at least one lifetime partner compared to HaBIDS (Table 3, Supplementary Table S4, Figure S4b).
Same-sex partners during lifetime and in the last 12 months
Within HaBIDS, 121 participants (11%; 38 men, 83 women) reported at least one same-sex sexual partner in their lifetime (in addition to potential opposite-sex sexual partners). Among participants who reported at least one same-sex sexual partnership, HaBIDS participants had a median of 2 lifetime same-sex partners (IQR 1–4). The number of partners was similar in NSFG (IRR 1.02, 95%CI 0.82–1.26) but higher in SBG (IRR 1.70, 95%CI 1.30–2.22) and Natsal (IRR 1.91, 95%CI 1.54–2.38; Fig. 5; Table 3).
Fifty percent of HaBIDS participants with at least one lifetime same-sex sexual partner, reported one or more same-sex sexual partner in the last 12 months (Supplementary Table S6). NSFG participants reported lower numbers of same-sex sexual partners in the last 12 months compared to HaBIDS (IRR 0.61, 95%CI 0.43–0.87); this was not the case for Natsal (IRR 0.90, 95%CI 0.63–1.29). The number of new same-sex partners among those participants with a same-sex sexual partner in the past 12 months did not differ between Natsal and HaBIDS (IRR 1.38, 95%CI 0.73–2.54; Table 3; Supplementary Table S7).
Participants with both-sex sexual experience during lifetime and in the last 12 months
One hundred and thirteen (9%) of the HaBIDS participants reported to have had at least one opposite- and one same-sex sexual partner at some point during their lives. This percentage was similar in NSFG (10%; OR 1.05, 95%CI 0.86–1.30), but considerably lower in SBG (6%; OR 0.62, 95%CI 0.48–0.82) and Natsal (5%, OR 0.53, 95%CI 0.43–0.66). Among those participants with both-sex sexual experience, HaBIDS participants reported to have had a median of seven lifetime partners (IQR 4–11; Supplementary Table S8). The number of lifetime partners was higher in the other three studies (NSFG IRR 2.01, 95%CI 1.67–2.40; SBG IRR 2.31, 95%CI 1.83–2.92; Natsal IRR 2.81, 95%CI 2.33–3.37; Table 3)