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Table 2 Incidence rate (IR) and incidence rate ratio (IRR)

From: Real-world effectiveness of long-acting injections for reducing recurrent hospitalizations in patients with schizophrenia

 

Non-medication

Oral medication alone

LAI medication

Overall

 Observational period (person-years)

80,104

169,948

 

5612

 

 Outcome event (count)

36,721

63,390

 

1478

 

1 episode

 Observational period

61,884

114,631

 

2895

 

 Outcome event

22,593

32,045

 

601

 

2 episode

 Observational period

11,992

33,385

 

1476

 

 Outcome event

7187

13,999

 

401

 

3 episode

 Observational period

3476

12,042

 

635

 

 Outcome event

3124

7098

 

213

 

4 or more episode

 Observational period

2752

9889

 

606

 

 Outcome event

3817

10,248

 

263

 

IR

 Overall

4.58 (4.47–4.70)

3.73 (3.67–3.79)

 

2.63 (2.39–2.91)

 

 1 episode without SGA before

2.68 (2.55–2.81)

2.21 (2.10–2.32)

 

1.57 (1.01–2.47)

 

 1 episode with SGA before

4.28 (4.13–4.43)

2.94 (2.87–3.01)

 

2.15 (1.85–2.50)

 

 2 episode

5.99 (5.64–6.38)

4.19 (4.04–4.36)

 

2.71 (2.24–3.29)

 

 3 episode

8.98 (8.03–10.06)

5.90 (5.55–6.27)

 

3.33 (2.51–4.47)

 

 4 or more episode

13.88 (12.28–15.74)

10.36 (9.71–11.07)

 

4.31 (3.25–5.79)

 
 

Only oral medication IR/non-medication IR

LAI IR/non-medication IR

Overall

Reference

0.81 (0.80–0.83)

< 0.001

0.57 (0.52–0.63)

< 0.001

 1 episode

Reference

0.77 (0.75–0.78)

< 0.001

0.57 (0.49–0.66)

< 0.001

 2 episode

Reference

0.70 (0.67–0.73)

< 0.001

0.45 (0.37–0.55)

< 0.001

 3 episode

Reference

0.66 (0.62–0.70)

< 0.001

0.37 (0.28–0.50)

< 0.001

 4 or more episode

Reference

0.75 (0.70–0.80)

< 0.001

0.31 (0.23–0.42)

< 0.001

 

LAI IR/only oral medication IR

Overall

 

Reference

 

0.71 (0.64–0.78)

< 0.001

 1 episode

 

Reference

 

0.74 (0.65–0.86)

< 0.001

 2 episode

 

Reference

 

0.65 (0.53–0.79)

< 0.001

 3 episode

 

Reference

 

0.56 (0.43–0.76)

< 0.001

 4 or more episode

 

Reference

 

0.42 (0.31–0.56)

< 0.001

  1. LAI long-acting injection, SGA second-generation antipsychotics, (95% confidence interval)
  2. IR incidence rate \(= \frac{\text{re - hospitalization events}}{{10 {\text{person - years}}}}\) (95% confidence interval)
  3. \({\text{Only oral medication IR/non - medication IR}} = \frac{\text{Only oral medication incidence rate}}{\text{Non - medication incidence rate}}\) (95% confidence interval)
  4. \({\text{LAI IR}}/{\text{non - medication IR}} = \frac{\text{LAI incidence rate}}{\text{Non - medication incidence rate}}\) (95% confidence interval)
  5. \({\text{LAI IR/only oral medication IR}} = \frac{\text{LAI incidence rate}}{\text{Only oral medication incidence rate}}\) (95% confidence interval)