Table 1 Patient characteristics of the clozapine exposure and non-exposure groups

Sex, Man

21 (32.3%)

171 (42.7%)

.135

Number of appendicitis cases

5 (7.7%)

5 (1.3%)

.007

Incidence of appendicitis during the observation period, (per 1,00,000 person-years)

863

124

-

Incidence of appendicitis during clozapine administration (per 1,00,000 person-years)

2086

-

-

Age at the start of clozapine administration

32.3 (23.1–50.4)

-

-

Length of disease duration at the start of clozapine administration (years)

9.3 (2.9–16.6)

-

-

Duration of clozapine administration (months)

41.5 (8.6–73.7)

-

-

Withdrawal of clozapine administration due to adverse events

18 (27.7%)

-

-

Maximum administration dose of clozapine (mg)

300 (200–525)

-

-

Age at the start of treatment for schizophrenia

20.5 (18.5–26.5)

25.2 (19.8–32.7)

 < .001

Age at the first visit to our hospital

25.8 (19.9–35.3)

30.1 (23.0–40.9)

.008

Length of disease duration (years)

13.3 (7.3–20.8)

12.3 (4.7–23.3)

.665

Length of the observation period (years)

7.4 (2.6–13.1)

6.7 (1.3–15.5)

.652

Coexistence of diabetes mellitus

0 (0%)

26 (6.5%)

.036

Regular user of anticholinergic drugs

5 (7.7%)

119 (29.8%)

 < .001

Regular user of benzodiazepines

43 (66.2%)

289 (72.3%)

.305

Regular user of corticosteroids

1 (1.5%)

7 (1.8%)

1.000

Regular user of laxatives

56 (86.2%)

116 (29.0%)

 < .001

Regular user of mood stabilizers

15 (23.1%)

48 (12.0%)

.029

Regular user of NSAID_S

3 (4.6%)

36 (9.0%)

.335

Regular user of NaSSA

1 (1.5%)

9 (2.3%)

1.000

Regular user of SSRIs/SNRIs

3 (4.6%)

31 (7.8%)

.605

Regular user of TCA

0 (0%)

5 (1.3%)

1.000