Table 4.
Age of onset of comorbid disorders, as a function of the number of specific phobia subtypes
| Comorbid disorder | Number of subtypes | Test of linear effect (whole sample) | Test of linear effect (SP cases only) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4+ | |||||
| Median (IQR) | Median (IQR) | Median (IQR) | Median (IQR) | Median (IQR) | OR (95% CI) | p value | OR (95% CI) | p value | |
| Agoraphobia | 21 (13–35) | 21 (13–39) | 20 (13–40) | 16 (8–31) | 12 (8–17) | 1.2* (1.1–1.2) | < 0.001 | 1.3* (1.2–1.4) | < 0.001 |
| Generalized anxiety disorder | 39 (26–54) | 37 (24–52) | 35 (21–52) | 33 (20–44) | 28 (18–46) | 1.2* (1.1–1.2) | < 0.001 | 1.2* (1.1–1.2) | < 0.001 |
| Panic disorder | 33 (21–49) | 29 (19–41) | 35 (18–60) | 24 (14–41) | 18 (11–27) | 1.2* (1.2–1.3) | < 0.001 | 1.2* (1.1–1.3) | < 0.001 |
| Post-traumatic stress disorder | 36 (21–54) | 33 (20–49) | 36 (19–53) | 35 (19–75) | 33 (19–64) | 1.1* (1.0–1.1) | 0.002 | 1.1 (1.0–1.2) | 0.166 |
| Separation anxiety disorder | 19 (10–31) | 19 (8–29) | 18 (8–30) | 14 (8–36) | 17 (8–28) | 1.0 (1.0–1.1) | 0.074 | 1.0 (1.0–1.1) | 0.235 |
| Social anxiety disorder | 14 (9–18) | 13 (10–16) | 13 (8–16) | 13 (8–17) | 12 (7–15) | 1.2* (1.1–1.2) | < 0.001 | 1.3* (1.3–1.4) | < 0.001 |
| Major depression/dysthymia | 38 (25–53) | 33 (22–48) | 34 (21–51) | 30 (18–50) | 29 (15–46) | 1.2* (1.1–1.2) | < 0.001 | 1.1* (1.0–1.2) | 0.001 |
| Bipolar disorder | 25 (18–38) | 26 (18–44) | 28 (19–45) | 33 (20–45) | 24 (18–32) | 1.0 (1.0–1.1) | 0.169 | 1.2* (1.1–1.3) | 0.001 |
Median age of onset was determined using the actuarial method. Differences in age of onset were tested with a discrete-time logistic regression, with the sample limited to participants who developed the comorbid disorder, and with number of early phobia subtypes time-varying until age 13
*p < 0.005