### Mediator model

Call:
lm(formula = bili ~ trt, data = data)

Residuals:
    Min      1Q  Median      3Q     Max 
-3.4000 -2.5000 -1.7000  0.4434 24.3000 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)  
(Intercept)   2.2132     0.8784   2.520   0.0123 *
trt           0.7434     0.5532   1.344   0.1801  
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 4.594 on 274 degrees of freedom
Multiple R-squared:  0.006548,	Adjusted R-squared:  0.002923 
F-statistic: 1.806 on 1 and 274 DF,  p-value: 0.1801

### Outcome model

Call:
MASS::glm.nb(formula = platelet ~ trt + bili + trt:bili, data = data, 
    init.theta = 7.58167734, link = log)

Coefficients:
             Estimate Std. Error z value Pr(>|z|)    
(Intercept)  5.579867   0.089778  62.152   <2e-16 ***
trt          0.007436   0.055605   0.134    0.894    
bili        -0.019952   0.018332  -1.088    0.276    
trt:bili     0.008113   0.010471   0.775    0.438    
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

(Dispersion parameter for Negative Binomial(7.5817) family taken to be 1)

    Null deviance: 285.09  on 275  degrees of freedom
Residual deviance: 282.50  on 272  degrees of freedom
AIC: 3290.2

Number of Fisher Scoring iterations: 1


              Theta:  7.582 
          Std. Err.:  0.653 

 2 x log-likelihood:  -3280.226 
### Mediation analysis 
              est          se          Z         p       lower      upper
cde   0.022553425 0.057916516  0.3894127 0.6969709 -0.09096086 0.13606771
pnde  0.037166743 0.053560991  0.6939144 0.4877359 -0.06781087 0.14214436
tnie -0.001151555 0.007215852 -0.1595869 0.8732065 -0.01529437 0.01299126
tnde  0.045851847 0.054117106  0.8472709 0.3968442 -0.06021573 0.15191943
pnie -0.009836660 0.010124180 -0.9716006 0.3312493 -0.02967969 0.01000637
te    0.036015187 0.053435742  0.6739906 0.5003173 -0.06871694 0.14074732
pm   -0.032572146 0.211968550 -0.1536650 0.8778739 -0.44802287 0.38287858
      exp(est) exp(lower) exp(upper)
cde  1.0228097  0.9130534   1.145759
pnde 1.0378661  0.9344372   1.152743
tnie 0.9988491  0.9848220   1.013076
tnde 1.0469193  0.9415614   1.164066
pnie 0.9902116  0.9707564   1.010057
te   1.0366716  0.9335909   1.151134
pm          NA         NA         NA

Evaluated at:
avar: trt
 a1 (intervened value of avar) = 2.3
 a0 (reference value of avar)  = 1.1
mvar: bili
 m_cde (intervend value of mvar for cde) = 1.4
cvar: 
 c_cond (covariate vector value) = 

Note that effect estimates can vary over m_cde and c_cond values when interaction = TRUE.