The sample for the period 2018-2021 consisted of 55.4% female participants (n=2840). The year with the highest number of subjects was 2020, accounting for 37.6% of the students (n=1928), followed by 2021 with 24% (n=1234). The average age of the subjects was 18.9 years (+2.2), ranging from 16 to 49 years. Among the responses, 36.7% were from the Faculty of Engineering and Agronomy (n=1853), 31.1% from the Faculty of Medicine and Dentistry (n=1572), and 32.2% from the Faculty of Social and Legal Sciences (n=1630). Regarding educational attainment in the household, 15.9% had primary education (n=313), 47.6% had secondary education (n=938), and 36.5% had tertiary education (n=718). A total of 33.2% identified themselves as having Mapuche ancestry (n=933) (Table 1).
Table 1. General, sexual activity, and related practices data.
Variables
|
2018
N (%)
|
2019
N (%)
|
2020
N (%)
|
2021
N (%)
|
Total
N (%)
|
General
|
1212 (23.6)
|
757 (14.8)
|
1928 (37.6)
|
1234 (24)
|
5131 (100)
|
Gender
|
|
|
|
|
|
Female
|
698 (57.6)
|
478 (63.3)
|
1006 (52.2)
|
658 (53.3)
|
2840 (55.4)
|
Male
|
514 (42.4)
|
277 (36.7)
|
922 (47.8)
|
576 (46.7)
|
2289 (44.6)
|
Faculty
|
|
|
|
|
|
Eng. & Agro.
|
454 (37.5)
|
285 (37.8)
|
604 (31.9)
|
510 (42.6)
|
1853 (36.7)
|
Med. & Dent.
|
395 (32.6)
|
270 (35.8)
|
545 (28.8)
|
362 (30.2)
|
1572 (31.1)
|
Soc. & Leg. Sc.
|
363 (30.0)
|
199 (26.4)
|
743 (39.3)
|
325 (27.2)
|
1630 (32.2)
|
Educational attainment
|
Primary
|
109 (15.6)
|
64 (13.4)
|
140 (17.7)
|
-
|
313 (15.9)
|
Secondary
|
355 (50.9)
|
224 (46.9)
|
359 (45.3)
|
-
|
938 (47.6)
|
Tertiary
|
234 (33.5)
|
190 (39.7)
|
294 (37.1)
|
-
|
718 (36.5)
|
Mapuche ethnic group
|
|
|
|
|
|
No
|
-
|
-
|
1148 (65.7)
|
732 (68.7)
|
1880 (66.8)
|
Yes
|
-
|
-
|
599 (34.3)
|
334 (31.3)
|
933 (33.2)
|
Started sexual activity
|
|
|
|
|
|
Yes
|
676 (55.8)
|
415 (54.8)
|
1232 (63.9)
|
687 (55.7)
|
3010 (58.7)
|
No
|
536 (44.2)
|
342 (45.2)
|
696 (36.1)
|
547 (44.3)
|
2121 (41.3)
|
Sexual activity <15
|
Yes
|
68 (10.1)
|
24 (10.7)
|
116 (9.9)
|
81 (12.1)
|
289 (10.6)
|
No
|
603 (89.9)
|
200 (89.3)
|
1060 (90.1)
|
587 (87.9)
|
2450 (89.4)
|
Use condom
|
|
|
|
|
|
Yes
|
-
|
142 (62.8)
|
748 (63.0)
|
469 (70.1)
|
1359 (65.3)
|
No
|
-
|
84 (37.2)
|
439 (37.0)
|
200 (29.9)
|
723 (34.7)
|
Conceived last 12 mos.
|
|
|
|
|
|
Yes
|
-
|
6 (2.7)
|
19 (1.6)
|
8 (1.2)
|
33 (1.6)
|
No
|
-
|
219 (97.3)
|
1168 (98.4)
|
661 (98.8)
|
2048 (98.4)
|
PAP test
|
|
|
|
|
|
Yes
|
-
|
18 (13.1)
|
88 (14.9)
|
52 (15.5)
|
158 (14.8)
|
No
|
-
|
119 (86.9)
|
504 (85.1)
|
284 (84.5)
|
907 (85.2)
|
Breast exam
|
|
|
|
|
|
Yes
|
-
|
-
|
88 (14.7)
|
57 (16.8)
|
145 (15.5)
|
No
|
-
|
-
|
511 (85.3)
|
282 (83.2)
|
793 (84.5)
|
STI last 12 mos.
|
|
|
|
|
|
Yes
|
-
|
4 (1.0)
|
12 (1.0)
|
151 (22.6)
|
167 (7.4)
|
No
|
-
|
411 (99.0)
|
1175 (99.0)
|
518 (77.4)
|
2104 (92.6)
|
HIV test
|
|
|
|
|
|
Yes
|
-
|
121 (29.2)
|
383 (32.3)
|
177 (26.5)
|
681 (30.0)
|
No
|
-
|
293 (70.8)
|
804 (67.7)
|
492 (73.5)
|
1589 (70.0)
|
Gender Perspective
Among the female participants, 55.9% reported having had sexual activity (n=1588), while among males, 62% reported sexual activity (n=1420), indicating that males had 1.3 times more sexual activity than females (OR=1.29, 95% CI: [1.15;1.44], χ²=19.58, p<0.001). The average age at first sexual activity was 16.3 years (+1.6) for females and 16.2 years (+1.5) for males (t=2.35, df=2736, p=0.02, 95% CI: [0.02/0.26], d=1.55). 9.9% of females initiated sexual activity before the age of 15 (n=142), compared to 11.3% of males (n=147) (OR=1.16, 95% CI: [0.91;1.48], χ²=1.39, p=0.24). Regarding condom use in the last sexual encounter, 60.1% of females reported using a condom (n=640), while 70.7% of males reported using a condom (n=718), indicating that males used condoms 1.6 times more often than females (OR=1.60, 95% CI: [1.33;1.92], χ²=25.65, p<0.001). Pregnancy or impregnating someone in the last 12 months was reported by 1.9% of females (n=20) and 1.2% of males (n=12) (OR=1.60, 95% CI: [0.78; 3.30], χ²=1.67, p=0.20). 8.5% of females who reported sexual activity were diagnosed with a sexually transmitted infection (STI) in the last 12 months (n=101), compared to 6.1% of males (n=66), indicating that females had 1.5 times higher STI diagnosis than males (OR=1.43, 95% CI: [1.0;1.9], χ²=4.85, p=0.028). Regarding HIV testing, 32.4% of females reported undergoing HIV testing (n=384), compared to 27.4% of males (n=297), indicating that females were 1.3 times more likely to undergo HIV testing than males (OR=1.27, 95% CI: [1.05; 1.52], χ²=6.61, p=0.01).
Ethnicity Perspective
Among students who identified themselves as Mapuche, 53.2% reported initiating sexual activity (n=496), compared to 63.2% among non-Mapuche students (n=1188), indicating that non-Mapuche students had 1.5 times higher sexual activity initiation than Mapuche students (OR=1.51, 95% CI: [1.29;1.77], χ²=26.11, p<0.01). The average age at first sexual activity was 16.36+1.65 for Mapuche students and 16.23+1.52 for non-Mapuche students, with no statistically significant difference between these values (t=1.64, df=1612, p=0.10, 95% CI: [-0.03/0.31]). 10.3% of Mapuche students initiated sexual activity before the age of 15 (n=49), compared to 11.2% of non-Mapuche students (n=128) (OR=1.1, 95% CI: [0.77; 1.55], χ²=0.27, p=0.60). Regarding condom use in the last sexual encounter, 63% of Mapuche students reported using a condom (n=303), compared to 66.6% of non-Mapuche students (n=763) (OR=1.17, 95% CI [0.94; 1.47], χ²=1.99, p=0.16). The percentage of pregnancy among Mapuche and non-Mapuche students was 2.1% (n=10) and 1.1% (n=13) respectively (OR=1.85, 95% CI [0.81; 4.25], χ²=2.16, p=0.14). Mapuche females reported undergoing breast examination in 14.7% of cases (n=40) and Pap smear in 14.2% of cases (n=38), while non-Mapuche females reported undergoing these examinations in 15% (n=79) and 14.8% (n=77) respectively (OR breast examination=1.02, 95% CI [0.68;1.54], χ²=0.009, p=0.923) (OR Pap smear=1.05, 95% CI [0.69/1.59], χ²=0.047, p=0.829). The percentage of Mapuche students diagnosed with STIs in the last 12 months was 7.9% (n=38), compared to 8.3% (n=95) among non-Mapuche students (OR=1.05, 95% CI [0.71/1.56], χ²=0.071, p=0.79). HIV testing was performed by 32.8% of Mapuche students (n=158) and 28.4% of non-Mapuche students (n=325) (OR=1.23, 95% CI [0.98; 1.55], χ²=3.23, p=0.07).
Before and during the COVID-19 Pandemic
When comparing the years 2018 and 2019 with the years 2020 and 2021, it was observed that in the first period, 55.4% had initiated sexual activity (n=1091), compared to 60.7% during the pandemic years (second period) (n=1919) (OR=1.24, 95% CI [1.11/1.39], χ²=13.95, p<0.001). The average age of sexual activity initiation in the first period was 16.29+1.59, compared to 16.26+2.69 in the second period (t=0.42, p=0.68, 95% CI [-0.09; 0.15]). 10.3% of students initiated sexual activity before the age of 15 in 2018 and 2019 (n=92), compared to 10.7% of students during the pandemic (n=197) (OR=1.04, 95% CI [0.80/1.36], χ²=0.10, p=0.75). Regarding condom use in the first period, 62.8% of students used a condom in their last sexual encounter (n=142), compared to 65.6% in the second period (n=1217) (OR=1.13, 95% CI [0.84/1.50], χ²=0.68, p=0.41). Pregnancy in the last 12 months was reported by 2.7% of students in the first period (n=6), compared to 1.5% in the second period (n=27) (OR=1.86, 95% CI [0.76/4.55], χ²=1.89, p=0.17). In the 2018-2019 period, 13.1% of female students underwent Pap smears (n=18), and 29.2% of students underwent HIV testing in general (n=121), while in the second period, 15.1% of female students underwent Pap smears (n=140) (OR=1.18, 95% CI [0.69/1.99], χ²=0.36, p=0.55), and 30.2% of students underwent HIV testing in general (n=560) (OR=1.05, 95% CI [0.83/1.32], χ²=0.14, p=0.70). STIs were diagnosed in 1% of students in the first period (n=4), and in 8.8% in the second period (n=163), indicating 10.78 times more cases in the second period compared to the first (OR=9.89, 95% CI [3.65/26.83], χ²=30.43, p<0.001).
Independent years
Analyzing the years independently, the highest percentage of students who initiated sexual activity was in 2020 with 63.9% (n=1232), while the lowest percentage was in 2019 with 54.8% (n=415), indicating 1.5 times more likelihood of students initiating sexual activity in 2020 compared to 2019 (OR(2020/2019)=1.46, 95% CI: [1.23;1.73], χ²=18.89, p<0.001). The percentages of initiating sexual activity before the age of 15 remained consistent, with the lowest percentage in 2020 (9.9%) (n=116) and the highest percentage in 2021 (12.1%) (n=81) (OR(2020/2021)=1.26, 95% CI: [0.93;1.70], χ²=2.284, p=0.131). The age of sexual activity initiation was similar across all years: 2018 (16.29+1.64), 2019 (16.28+1.45), 2020 (16.32+1.56), and 2021 (16.17+1.49) (F=1.42, p=0.24). The year 2021 reported the highest percentage of condom use, with 70.1% (n=469), while 2019 reported the lowest use, with 62.8% of students using condoms in their last sexual encounter (n=142), indicating 1.39 times more condom use in 2021 than in 2019 (OR(2021/2019)=1.39, 95% CI: [1.01;1.90], χ²=4.13, p=0.042) (Table 1).
The trend of pregnancy in the last 12 months among students remained consistent across the years, with 2.7% (n=6), 1.6% (n=19), and 1.2% (n=8) in 2019, 2020, and 2021 respectively (OR(2019/2021)=2.26, 95% CI: [0.78;6.58], χ²=2.36, p=0.12). Among females who initiated sexual activity, the trend regarding Pap smear examination showed a slight increase, with 13.1% in 2019 (n=18), 14.9% in 2020 (n=88), and 15.5% in 2021 (n=52) (OR(2021/2019)=1.21, 95% CI: [0.68; 2.16], χ²=0.42, p=0.52). Among females who underwent physical breast examination at any time, the trend in 2020 and 2021 was 14.7% (n=88) and 16.8% (n=57) respectively (OR(2020/2021)=1.17, 95% CI: [0.82; 1.69], χ²=0.75, p=0.39) (Table 1).
In 2021, the highest percentage of students diagnosed with STIs in the last 12 months was reported, with 22.6% (n=151), compared to 1% (n=4) and 1% (n=12) in 2019 and 2020 respectively. When comparing 2021 with 2020, there was a 28.54 times higher likelihood of STIs in 2021 (OR(2021/2020)=28.54, 95% CI: [15.71;51.85], χ²=248.26, p<0.001). HIV testing was performed by students in all three years with some variations, with the lowest percentage in 2021 (26.5%) (n=177) and the highest percentage in 2020 (32.3%) (n=383), indicating 1.32 times more HIV testing in 2020 than in 2021 (OR(2020/2021)=1.32, 95% CI: [1.07;1.63], χ²=6.85, p=0.009) (Table 1).
Specific Associations
Furthermore, the association between condom use in the last sexual encounter and being diagnosed with STIs was analyzed, and no association was found (OR=1.14, 95% CI: [0.82;1.59], χ²=0.64, p=0.42). These trends remained consistent across genders, ethnicities, and years.
Moreover, the association between undergoing HIV testing and being diagnosed with STIs was identified, showing an association when analyzing the overall data, with 91% of subjects diagnosed with STIs undergoing HIV testing (OR=30.15, 95% CI: [17.58;51.71], χ²=319.59, p<0.001). Among females diagnosed with STIs, 89.1% underwent HIV testing, compared to 93.9% of males, while 27.1% of females not diagnosed with STIs underwent HIV testing, compared to 23.1% of males (OR females=22.01, 95% CI: [11.61;41.76], χ²=162.29, p<0.001) (OR males=51.58, 95% CI: [18.57;143.26], χ²=156.23, p<0.001). Similar results were observed in both ethnic groups, with STI diagnosis and HIV testing percentages of 86.8% in Mapuche students and 90.5% in non-Mapuche students (OR Mapuche=16.79, 95% CI: [6.41;43.99], χ²=54.53, p<0.001) (OR non-Mapuche=32.43, 95% CI: [16.08;65.40], χ²=196.80, p<0.001). In the pandemic and pre-pandemic years, the same pattern was observed, with 100% of diagnosed cases undergoing HIV testing in the pre-pandemic period and 90.8% in the pandemic period (Fisher's exact test p=0.007) (OR(2020/2021)=30.68, 95% CI: [17.83;52.78], χ²=311.73, p<0.001).