A cross-sectional study of risk factors associated with wound strength in post midline laparotomy HIV positive patients at the University Teaching Hospital,Lusaka

Introduction
Delayed-healing in abdominal surgical wounds may be detrimental to patients and the health care. The author set out to investigate the effects of CD4+ count, serum albumin and haemoglobin (HB) levels on wound strength in HIV positive patients. Wound strength in this study is used to determine the rate of wound healing.
Objectives
To determine some risk factors associated with post laparotomy wound strength and to investigate the relationship between CD4+ count and wound strength in HIV positive patients. To establish the prevalence of wound break down and to study other risk factors associated with wound strength in wound healing.
Methods
This was a cross-sectional study done from January to June 2014 at UTH Surgery Department. HIV positive patients who underwent abdominal surgery during the study period were enrolled to meet the sample size of 56. A structured questionnaire was used to gather information. Blood was drawn from enrolled patients for laboratory investigations namely CD4+ count, serum albumin and haemoglobin. On Day 10 post surgery wound strength was measured using a Digital Force Gauge. Data analyzed using frequency tables, correlation coefficient test and multiple linear regression analysis to determine associated factors.
Results
In this study wound tensile strength of patients 10 days after abdominal surgery ranged from 0.38 to 6.33N. The mean wound strength was 2.88 (SD=1.69030), the mode was 2.89N. The following factors were associated with wound strength; CD4+ count, serum albumin and haemoglobin (HB). Patients’ CD4+ count ranged from 23 to 600 with a mean of 217.2679 (SD=131.57431), haemoglobin (HB) ranged from 5.4 to 14.2g/dl with a mean of 9.1286 (SD=2.14525) and serum albumin ranged from 13.0 to 49.0mmol/L with a mean of 29.1982 (SD=8.67629). Correlation coefficient test conducted at significant level of 0.01 showed that there was a significant positive association between CD4+ count and wound strength (rho=0.944 (n=56); p=0.001). There was also a significant positive association between haemoglobin (HB) and wound strength (rho=0.811 (n=56); p=0.001). The results further confirmed a significant positive association between serum albumin and wound strength (rho=0.711 (n=56); p=0.001). Multiple linear regression analysis was used to develop a model for predicting wound strength. The results showed that each of the predictor variables had a significant (p<0.1) zero-order correlation with wound strength, but only CD4+ count and serum albumin had significant (p<0.01) partial effects in the full model. The three predictor model accounted for 90.1% of the variance wound strength, F (3, 52) =157.398, p<0.001, R2 =0.901, 95% CI [-1.157, 0.300]. The results showed that CD4+ count was the best predictor of wound strength followed by serum albumin.