Table 1 Model inputs to estimate health outcomes of infections associated with active injection drug use in the United States^a

Population

 Initial calendar year

2015

^b

 Time horizon, months

60

^b

 Proportion female (%)

32.5

[24]

 Initial age, mean years (SD)

30 (2.5)

^b

Drug Use Behavior

 Initial Opioid Use Proportion (%)

[24]

  Low-risk state

62.9

  Medium-risk state

2.1

  OUD

35.0

 Monthly Transition Probabilities (%)

  Low to Medium

-^c

  Low to OUD

-^c

  Medium to OUD

-^c

  OUD to Remission

2.19

^d

  Remission to OUD

5.75

[38]

Serious Bacterial Infections

IDU

Non-IDU

 Monthly Transition Probabilities

  Bacterial infection incidence (%), varies by calendar year

0.6915–0.8672

0.0262–0.0284

[4]

  Infection proportion (%)

[4]

   CNS infection

2.3

0.9

   Endocarditis

5.4

1.0

   Osteomyelitis

6.3

3.6

   Skin/soft tissue infection

86.0

94.6

  Cure from bacterial infection (%)

80.9

97.4

[25]

HIV

IDU

Non-IDU

 Initial HIV Probabilities

  HIV prevalence (%)

3.0

0.4

[26]

  CD4 distribution (%)

[10, 27]

   High CD4 (≥ 500 cells/mm³)

30.5

41.0

   Medium CD4 (200–499 cells/mm³)

29.9

16.0

   Low CD4 (< 200 cells/mm³)

38.6

43.0

  Aware of status if HIV positive (%)

92.7

83.5

[26]

  On ART (%)

47.7

57.5

[28]

 Monthly Transition Probabilities

  Monthly HIV incidence (%), varies by calendar year

0.0355–0.0382

0.0010–0.0012

[26]

  Aware of status if HIV positive (%)

19.6

14.4

[26]

  Start ART (%)

5.3

6.9

[28]

  Stop ART (%)

1.7

1.0

[28]

  CD4 Transitions (%)

On ART

Off ART

[10]

   High to Medium CD4

1.14

1.24

   High to Low CD4

0.01

-

   Medium to High CD4

1.61

-

   Medium to Low CD4

0.64

7.00

   Low to Medium CD4

0.03

-

   Low to High CD4

2.66

-

HCV

IDU

Non-IDU

 Initial HCV Probabilities

  HCV prevalence (%)

33.5

1.1

[5, 20]

  Liver fibrosis stage for people starting with HCV (%)

[20]

   F0

27.2

   F1

33.4

   F2

17.1

   F3

11.1

   F4

9.6

   Decompensated cirrhosis

1.4

   Hepatocellular carcinoma

0.2

 Monthly Transition Probabilities

  Monthly HCV incidence (%), varies by calendar year

0.1359–0.2024

0.0002–0.0005

[29]

  % of acute HCV that clear spontaneously

2.4

[35]

  Liver fibrosis transitions (%)

HCV+

HCV-

[20]

   F0 to F1

0.9386

-

   F1 to F2

0.7105

-

   F2 to F3

1.0316

-

   F3 to F4

1.0222

-

   F4 to decompensated cirrhosis

0.2449

0.0669

   F4 to hepatocellular carcinoma

0.1174

0.0418

   Decompensated cirrhosis to hepatocellular carcinoma

0.5851

Monthly Mortality Probabilities^e

 Background Mortality

Varies by age and sex

[18]

 Drug Use Mortality (%), varies by calendar year

[24]

  Low-risk state

0.0052–0.0070

  Medium-risk state

0.1057–0.2580

  OUD

0.0166–0.0355

 Bacterial Infection Mortality (%)

[4]

  CNS infection

3.6

  Endocarditis

5.8

  Osteomyelitis

1.5

  Skin/soft tissue infection

1.5

 HIV Mortality (%)

On ART

Off ART

[19, 21,22,23]

  High CD4 state

0.0013

0.0033

  Medium CD4 state

0.0024

0.0155

  Low CD4 state

0.0102

0.1936

 HCV Mortality (%)

[20]

  Decompensated cirrhosis

1.0

  Hepatocellular carcinoma

4.5