HOST Study – HIV in Orthopaedic Skeletal Trauma Study : protocol for a multicentre case-cohort study

Background: Human immunodeficiency virus (HIV) and antiretroviral therapy (ART) have both been shown to reduce bone mineral density, mineralisation and bone turnover. Our study group and other researchers have suggested that HIV may impair fracture healing, based on extrapolation from basic science. These observations prompted this study as the true effect of HIV and highly active antiretroviral therapy (HAART) on bone healing is very poorly understood and has not previously been investigated. Methods: HOST Study is a multicentre case-cohort study being undertaken at two orthopaedic trauma centres in Cape Town, South Africa. All adult patients older than 18 years with fresh (within 2 weeks of injury), closed and open, tibia and femur fractures who undergo intramedullary (IM) nailing for fracture fixation will be eligible for the study. Participants will be recruited over 24 months and undergo a baseline questionnaire, HIV testing and assessment of their bone mineral density (BMD). They will be followed up at 2 and 6 weeks, and at 3, 6, 9 and 12 months. All adult patients who develop delayed bone union at the 6-month follow-up will be considered cases. Adult patients who show evidence of radiological union at 6 months or less will be considered controls. We will then determine if HIV is a risk factor for the development of delayed bone union. HIV prevalence levels in the cases and controls will be summarised using IRR (incidence rate ratio) statistics with their 95% confidence intervals. Negative binomial regression methods will be used to adjust the IRR estimates for the possible effects of confounding factors and/or important covariates. Results: Outcomes from the primary manuscript will be disseminated through publications in academic journals and presentations at relevant orthopaedic conferences. We will communicate trial results to all participating sites. Participating sites will communicate results with patients who have indicated an interest in knowing the results. Trial registration number: ClinicalTrials.gov NCT03131947 Site of study: Groote Schuur Hospital and Tygerberg Hospital, Cape Town, South Africa


Introduction
Worldwide approximately 35.3 million people are HIV positive, with the highest prevalence seen in sub-Saharan Africa. 1 The introduction of antiretroviral therapy (ART) in 1997 has altered the course and nature of patients infected with HIV by increasing the duration of asymptomatic infection, and consequently patients with HIV are attaining close-to-normal life spans.However, despite these longer life expectancies, there is little evidence to advise the surgeon and patient about the effect of long-term immunosuppression on the fracture repair process in orthopaedic surgery. 2 HIV principally affects a patient's immunological status by reducing the host CD4 T cell count, resulting in an increase in the risk of a patient developing opportunistic infections.7][8][9] In the general population, it has been postulated that a reduced BMD is associated with a reduced speed of fracture healing. 10,11If this relationship were to hold true in the context of HIV, then they would not only be at an increased risk of fragility fracture, but also of subsequent delayed fracture healing and failure of fracture fixation.
A major factor known to affect fracture healing is local blood flow to the site of the injury.3][14] ART has also been reported to contribute to this pathology. 12[17] A small number of studies have investigated the role of HIV in the fracture-healing process.These have suggested that HIV and/ or ART are associated with delayed fracture healing and may result in non-union. 11,18The molecular and cellular mechanisms driving this process remain unclear and the true effect of HIV and ART on bone healing is very poorly understood.
Our study group has previously demonstrated an association between HIV infection and impaired fracture healing. 18,19urthermore, analysis of patients presenting to Queen Elizabeth Central Hospital, Blantyre, Malawi, for immediate fracture treatment and non-union surgery, indicates twice the frequency of HIV seropositivity in the non-union group (Figure 1) (personal communication -Professor WJ Harrison).Other researchers have suggested that HIV may impair fracture healing, based on extrapolation from basic science. 11hese observations prompted this study as the true effect of HIV on bone healing is very poorly understood and has not previously been thoroughly investigated.

Study objectives
Our primary objective is to establish whether HIV is a risk factor for the development of delayed bone union or non-union following a fracture.

Secondary objectives are:
• To assess other risk factors associated with delayed bone union or non-union in HIV-positive and -negative adults, e.g.BMD, ART

Funding:
The funding for this research study was supplied by the Wellcome Trust and AOUK.

Conflict of interest:
The authors declare they have no conflicts of interest that are directly or indirectly related to the research.

Study design
HOST Study is a multicentre case cohort study of patients undergoing fracture surgery within the Orthopaedic and Trauma Department at Groote Schuur Hospital (GSH) and Tygerberg Hospital (TBH), Cape Town, South Africa.

Patient selection and recruitment
Patients older than 18 years of age with fresh (within 2 weeks of injury), closed and open, tibia and femur fractures who undergo IM nailing for fracture fixation will be potentially eligible for inclusion in the study.Participants will undergo a baseline questionnaire, and established risk factors for delayed bone healing and nonunion will be recorded.The patients' full blood count, renal function, vitamin D level and albumin will be assessed.All patients will undergo HIV testing and a measurement of the patients CD4 count and viral load if positive.If a patient is found to have a new diagnosis of HIV, standard local hospital protocol will be followed, and the patient will be offered treatment.If the patient is already known to be HIV positive, their ART regimen will be recorded, if appropriate.Furthermore, all patients will have their BMD measured using a DEXA Heel Scanner, Calscan DXL.
X-rays will be performed at follow-up visits or if clinically required.Bone healing will be assessed using a validated X-ray scoring system -the Radiological Union Scoring system for the Tibia (RUST scoring system). 20,21An independent observer blinded to HIV status will assess radiological fracture union.Participants will be recruited over 24 months.
All adult patients treated with IM nailing of the tibia or femur and who develop delayed bone union at 6 months follow-up will be considered cases.Adult patients who show evidence of radiological union at 6 months or less will be considered controls.

Inclusion criteria
Patients will be eligible for this study if they: • Are older than 18 years of age • Evidence that the patient would be unable to adhere to study procedures, complete questionnaires or attend follow-up Patients who sustain injuries to areas of the body other than the lower limbs, which may affect the primary outcome measure, will have their injuries documented but the participants will still be included in the analysis.For patients with more than one lower limb injury that meets the inclusion criteria, each injury will be included as an individual case and entered separately into the study.

Study outcome
Primary study outcome: • Incidence of delayed bone union in HIV-positive and -negative patients Secondary study outcomes: • Incidence of non-union in HIV-positive and -negative patients • Other risk factors associated with delayed bone union or nonunion in HIV-positive and -negative adults, e.g.BMD, ART • Incidence of superficial, deep and late wound infections in HIVpositive and -negative patients • To quantify and draw inferences on observed differences in the DRI and general health-related quality of life after fracture healing following IM nailing fracture surgery in HIV-positive and -negative patients

Outcome definitions
Union: • Radiological union on RUST score (score of 3 on at least three cortices in AP, lateral, medial or posterior cortex -a total of 9 or more) within 6 months of surgery 20,21 Delayed bone union: • Impaired bone healing at six months (RUST score < 9) [22][23][24][25][26] • Non-union -one or both of the following: ▫ Need for further surgery to achieve union 22,23 ▫ Impaired bone healing at nine months (RUST score < 9) 20,21 Superficial wound infection • Superficial surgical site infection (SSI) The Center for Disease Control and Prevention definition of a 'superficial surgical site infection' is a wound infection involving the skin and subcutaneous tissue that occurs after 30 days of surgery (where day 1 = the procedure date). 27ASEPSIS (28) ASEPSIS scores >20 within 30 days of surgery

Deep wound infection
The Center for Disease Control and Prevention definition of a 'deep surgical site infection' is a wound infection involving the tissues deep to the skin that occurs within 30 days of injury (closed reduction of fracture) or 90 days (open reduction of fracture). 27

Late wound infection
This describes any late wound breakdown (>30 days for closed reduction of fractures or >90 days for openly reduced fractures) or sinus formation, or unexplained late pain with associated radiological changes consistent with peri-implant sepsis.This will be determined on clinic follow-up for those still under review.Those patients who do not present for follow-up will be phoned and asked about the above.

EuroQol EQ-5D-5L
The EuroQol EQ-5D is a validated measure of health-related quality of life, consisting of a five-dimension health status classification system and a separate visual analogue scale. 23An updated version of the EQ-5D with five response levels, the EQ-5D-5L, has recently been developed to enhance the responsiveness of the instrument to changes in patient health. 24

Disability Rating Index (DRI)
The DRI is a self-administered, 12-item Visual Analogue Scale questionnaire assessing the patients' own rating of their disability. 22his measure was chosen as it addresses 'gross body movements' rather than specific joints or body segments.Therefore, it will facilitate the assessment of patients with different fractures and injuries of the lower limbs.This outcome measure will not be taken for those patients with longer term (more than 4 weeks) impaired capacity.

Bone mineral density
• Normal -T score of <1 standard deviations (T score <−1) below the peak bone mass of a healthy young adult • Osteopaenia -T score of 1 to 2.5 standard deviations (T score −1 to −2.5) below the peak bone mass of a healthy young adult • Osteoporosis -T score of >2.5 standard deviations (T score <−2.5) below the peak bone mass of a healthy young adult

Follow-up
The full visit-assessment schedule for the study is provided in Table I.Participants will be followed up in the clinic during the 12-month period of follow-up (see study schedule Table I).At 12 months, this may be via phone where appropriate.X-rays will be performed at 3, 6 and 9 months or if clinically indicated.If a patient is confirmed to have united on RUST score at 3 months, they will be followed up in the clinic at 6 and 9 months and have a telephone consultation at 12 months.The same will be done for patients who are confirmed to have united at 6 and 9 months follow-up.
All patients who have not united by 3, 6 or 9 months will have a follow-up clinic visit at 12 months.If there is no evidence of union at 9 months on RUST score, or the patient has undergone a procedure or intervention to assist healing, they will be classified as non-union.The 12-month follow-up will be the final followup time point for the study, either face-to-face or via telephonic communication, even though a patient may need further clinical follow-up for other reasons.

Sample size
Our current register suggests that 400 patients are likely to undergo IM nailing of the tibia and femur at our centres over a two-year study period; 80% (320) are assumed to be eligible for inclusion.
On the basis of previous research, it is estimated that 85% (272) of the 320 patients will have union at 6 months (control), and 15% (48) will have delayed bone union (cases) 27,29 (Figure 2).
Assuming that 20% of the controls will be HIV-positive, 30 the sample size will have 82.8% power to detect a doubling of HIV prevalence in the cases compared to controls (from 20% to 40% at the 5% significance level).

Statistical methods
As all consenting patients who present during the study period for IM nailing of the tibia and femur will be recruited, HIV prevalence No delayed bone union (controls n=272)

Follow up 6 months
Analysis levels in the cases and controls will be summarised using IRR statistics with their 95% confidence intervals.Negative binomial regression methods will be used to adjust the IRR estimates for the possible effects of confounding factors and/or important covariates.

Basic descriptive analysis of demographic data and patient characteristics
Means and standard deviations are used for continuous data along a normal distribution, e.g.age.Level of education will be collected as continuous data and categorised by researchers.It will be analysed using graphs and tables.A confidence interval of 95% will be used.P values of <0.05 are considered statistically significant.

Data management
Standard operating procedures for data management without breach of confidentiality will be followed.Study participants will be assigned a unique study number at the time of recruitment, under which all electronic data will be captured.From this point, all data will be stored in a password-protected electronic database.Consent forms and case record forms will be kept in a locked filing cabinet in the research office.Only members of the study team (chief investigator, clinical officers and research nurse) will have access to these.Data will be entered into the electronic study database and managed by a data management team.All data exports will be stored on password-protected computers and backed up.The chief investigator and study supervisors will have control of access to the data.Only de-identified data will be exported for analysis.

Conclusion
This is the largest study of its type to assess the effect of HIV and ART on bone healing.It has been suggested that HIV causes delayed bone union and is a risk factor for the development of non-union following a fracture.If this hypothesis is shown to be true, fracture management could be tailored to optimise bone union during the fracture-healing phase in HIV-positive patients, improving outcomes and reducing the substantial social burden that occurs in these patients. 31If this hypothesis is shown to be incorrect then this study will demonstrate that HIV-positive patients can be treated in the same way as HIV-negative patients when managing orthopaedic skeletal trauma.

Figure 1 .
Figure 1.Numbers of patients presenting to QECH for intramedullary nailing for fresh fractures and non-unions: 2005-2007 Present within 2 weeks of injury • Sustained a closed or open fracture of the tibia or femur • Undergo IM nailing for fracture fixation Exclusion criteria Patients will be excluded from participation in this study in the case of: • Major head injury • Pre-surgical infection at the fracture site • Open injury for >48 hours before the first debridement • Severe burns • Pathological fracture

Figure 2 .
Figure 2. Study sample size Copyright: © 2018 Graham SM, et al.This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.