Incidence by Age at Diagnosis

HIV Surveillance Statistics, 2018, County of Orange, Health Care Agency

Figure 1.17 shows the distribution of PLWH by self-reported mode of exposure for five different age groups (by current age). Those currently under the age of 13 are discussed in Chapter 3. Those currently age 13 to 18 years are not discussed here due to fewer than 10 PLWH in any exposure group. The scale of the figure is set to exclude the graphing of MSM so the differences between the other modes of exposure can be shown.

 Mode of Exposure among 19-25 year-olds: The vast majority (77.5%) of 19-25 year-old PLWH reported being

exposed through MSM, followed by perinatal (6.8%) (not shown in Figure 1.17), heterosexual contact (6.4%), or

IDU (3.6%). There are fewer than 10 MSM/IDU.

 Mode of Exposure among 26-35 year-olds: The majority (82.6%) of PLWH ages 26-35 years reported being

exposed through MSM, followed by heterosexual contact (6.4%), MSM/IDU (4.3%), and IDU (1.8%). This group had the highest percentage of MSM exposure, as well as the highest percent with unknown exposure (3.7%).

 Mode of Exposure among 36-45 year-olds: For persons currently ages of 36-45 years, 73.4% reported being

exposed through MSM, followed by heterosexual contact (13.4%), MSM/IDU (5.2%), or IDU (4.7%).

 Mode of Exposure among 46-55 year-olds: The majority of 46-55 year-old PLWH reported being exposed

through MSM (71.6%) while 13.4% reported heterosexual contact, IDU (6.8%), or MSM/IDU (5.4%). This group had the highest percent with MSM/IDU exposure.

 Mode of Exposure among Individuals 56 years and over: For PLWH currently ages 56 years or older, 69.4%

reported being exposed through MSM, followed by heterosexual contact (14.0%), IDU (9.9%), or MSM/IDU (4.1%).

This age group had highest percentage who reported IDU or heterosexual contact as a mode of exposure.

15% Figure 1.17. Percent of PLWH by Current Age and Mode of Exposure, Orange County

Percent 12%

9%

6%

3%

MSM 0%

19-25 77.5%

IDU 3.6%

MSM/IDU Heterosexual 6.4% Unknown 2.5% 26-35 82.6% 1.8% 4.3% 6.4% 3.7% 36-45 73.4% 4.7% 5.2% 13.4% 2.5% 46-55 71.6% 6.8% 5.4% 13.4% 1.9% 56+ 69.4% 9.9% 4.1% 14.0% 1.5%

Those who are currently 0-12 years have a pediatric mode of exposure discussed in Chapter 3. Blank cells in the table above are due to fewer than 10 PLWH.

Incidence by Age at Diagnosis:

Of the 3,043 new cases of HIV diagnosed between 2009 and 2018, 10 were under the age of 13, 62 were between the ages of 13-18 years, 688 were between ages 19-25 years, 992 were between ages 26-35 years, 660 were between ages 36-45 years, 439 were between ages 46 and 55 years, and 192 were age 56 years or over at time of diagnosis.

Figure 1.18 shows the rate of cases diagnosed each year per 100,000 population by age at diagnosis within each age group. Persons age 0-12 years are displayed in the pediatric section.

 Case rates have declined since 2009-2011 for persons age 36-45 years and 46-55 years.  Persons aged 26-35 years consistently had the highest case rates except in 2009-2011 when person age 19-25 years

had a slightly higher rate.

 Persons 13-18 years and 56 years or older have consistently had the lowest case rates among age groups shown.