TEWL

T-Tests

T-tests showed that there is a significant difference in the following.

• Wound TEWL when compared between Placebo and Active

• Wound TEWL and Contralateral TEWL

• The difference between wound TEWL and Contralateral TEWL between Placebo and Active Groups.

# Perform the t-test
t_test_result <- t.test(wound ~ arm, data = VapoData)
# Perform a paired t-test
Wound_Contra_T <- t.test(VapoData$wound, VapoData$contra)
Wound_Contra_Dif_T <- t.test(dif ~ arm, data = VapoData)

print(Wound_Contra_T)

## 
##  Welch Two Sample t-test
## 
## data:  VapoData$wound and VapoData$contra
## t = 7.6021, df = 657.91, p-value = 1.008e-13
## alternative hypothesis: true difference in means is not equal to 0
## 95 percent confidence interval:
##  3.533259 5.994130
## sample estimates:
## mean of x mean of y 
##  23.88153  19.11784

print(Wound_Contra_Dif_T)

## 
##  Welch Two Sample t-test
## 
## data:  dif by arm
## t = 2.4395, df = 361.44, p-value = 0.01519
## alternative hypothesis: true difference in means between group Placebo and group Active is not equal to 0
## 95 percent confidence interval:
##  0.4169743 3.8844001
## sample estimates:
## mean in group Placebo  mean in group Active 
##              6.172558              4.021871

# Extract the p-value
p_value <- t_test_result$p.value

Graphs

Healed Wound Site TEWL Box plots by Arms

Was found to be significant between the means (p- 0.012)

Effect Plots

model <- glm(wound ~ 
                days_since_healed +
                arm +
                dm_duration +
                pet_owner +
                contra +
                bmi + 
                arm_exposure_days +
                hgba1c +
                smoking +
               charlson_comorbidity,
             family = gaussian,
            data = VapoData)
summary(model)

## 
## Call:
## glm(formula = wound ~ days_since_healed + arm + dm_duration + 
##     pet_owner + contra + bmi + arm_exposure_days + hgba1c + smoking + 
##     charlson_comorbidity, family = gaussian, data = VapoData)
## 
## Coefficients:
##                       Estimate Std. Error t value Pr(>|t|)    
## (Intercept)          16.713404   4.877936   3.426 0.000683 ***
## days_since_healed    -0.016342   0.007562  -2.161 0.031355 *  
## armActive            -1.308357   1.023745  -1.278 0.202076    
## dm_duration          -0.248308   0.054356  -4.568 6.79e-06 ***
## pet_ownerY            3.944361   1.138848   3.463 0.000598 ***
## contra                0.790520   0.074597  10.597  < 2e-16 ***
## bmi                  -0.146847   0.063161  -2.325 0.020635 *  
## arm_exposure_days    -0.021065   0.006539  -3.221 0.001393 ** 
## hgba1c               -0.191585   0.322025  -0.595 0.552261    
## smoking1              2.071082   1.131173   1.831 0.067946 .  
## smoking2              3.953487   1.279396   3.090 0.002158 ** 
## charlson_comorbidity  1.054041   0.372335   2.831 0.004905 ** 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## (Dispersion parameter for gaussian family taken to be 61.98666)
## 
##     Null deviance: 37982  on 368  degrees of freedom
## Residual deviance: 22129  on 357  degrees of freedom
##   (16 observations deleted due to missingness)
## AIC: 2583.8
## 
## Number of Fisher Scoring iterations: 2

Variable	Estimate	CI lower	CI upper	p-value
Current Smoker	3.953	1.446	6.461	0.002
Pet Owner	3.944	1.712	6.176	0.001
Former Smoker	2.071	-0.146	4.288	0.068
Charlson Comorbidity Index	1.054	0.324	1.784	0.005
Contralateral TEWL	0.791	0.644	0.937	0.000
Days After Healing	-0.016	-0.031	-0.002	0.031
Days in BAART	-0.021	-0.034	-0.008	0.001
BMI	-0.147	-0.271	-0.023	0.021
HgbA1c	-0.192	-0.823	0.440	0.552
Duration of DM	-0.248	-0.355	-0.142	0.000
Arm - Timolol	-1.308	-3.315	0.698	0.202

Global TEWL Increase

For every increase of 1 in wound TEWL it is expected that the contralateral TEWL will increase by 0.3456 ( p = \(2.2 * 10 ^{-16}\)). The correlation between wound TEWL and wound TEWL is r = 0.532 with a p value of \(2.18 * 10^{-28}\) . This lets us know that there is a moderately strong positive correlation that is significant between the two.

Similarly, when comparing the TEWL from five cm from the wound to five cm from the contralateral site. It is expected that every increase of 1 in the five cm away TEWL will increase the TEWL of the site 5 cm away from the contralateral site by 0.746 ( p-value \(2 * 10^{-16}\) ). There was a moderatley strong positive correlation between them, r = 0.662 ( p-value \(5.15 * 10^ {-48}\) ).

Scatter Plots Wound x Contra TEWL