What is the recommended approach for confirming HIV (Human Immunodeficiency Virus) status and initiating treatment in a patient with potential high-risk factors for HIV infection?

HIV Status Confirmation

All persons aged 15-65 years should undergo routine opt-out HIV screening at least once in their lifetime, with high-risk individuals tested every 3 months, using fourth-generation antigen/antibody combination assays followed by confirmatory testing before establishing diagnosis. 1, 2

Initial Screening Approach

Universal Screening Strategy

• Screen all adolescents and adults aged 15-65 years regardless of perceived risk factors, as risk-based screening has failed to identify 10-25% of HIV-positive individuals who report no high-risk behaviors. 1, 2
• Use routine opt-out screening in primary care settings, emergency departments, and for all pregnant women. 1, 2
• Do not make screening contingent on behavioral risk assessment, as approximately half of patients are diagnosed late when they cannot receive maximum benefit from antiretroviral therapy. 1

High-Risk Populations Requiring Frequent Testing

Screen every 3 months for: 1, 2

• Men who have sex with men (MSM)
• Transfeminine persons
• People who inject drugs
• Persons newly diagnosed with sexually transmitted infections or hepatitis C
• Sexual partners of HIV-infected persons
• Persons who exchange sex for money or drugs

Diagnostic Testing Algorithm

Step 1: Initial Screening Test

• Use fourth-generation HIV antigen/antibody combination assays that detect both HIV antibodies and p24 antigen, allowing detection of acute infection approximately 2 weeks earlier than antibody-only tests. 1, 2, 3, 4
• These assays have sensitivity and specificity greater than 99.5%. 5

Step 2: Confirmatory Testing (If Initial Test Reactive)

Critical: All reactive screening tests must be confirmed before establishing HIV diagnosis. 5, 1, 2

• Perform HIV-1/HIV-2 antibody differentiation immunoassay. 1, 2
• If antibody differentiation is negative or indeterminate, perform HIV RNA testing. 1, 2
• The conventional Western blot or immunofluorescent assay (IFA) remains acceptable for confirmation but is being replaced by the newer algorithm. 5

Common Pitfall: False-positive ELISA or rapid test results may rarely occur in patients with autoimmune disorders or pregnancy, but confirmatory testing will yield negative results in these cases. 5, 6

Rapid Testing Option

• Rapid HIV tests using blood or oral fluid specimens provide results in 5-40 minutes with sensitivity and specificity both greater than 99.5%. 5
• However, all positive rapid test results are preliminary and require confirmation with conventional methods before diagnosis. 5

Post-Diagnosis Baseline Evaluation

Essential Laboratory Assessment Before Treatment

Obtain immediately upon confirmed diagnosis: 1, 2, 7

HIV Disease Monitoring:

• HIV RNA (viral load) level to assess prognosis and establish baseline 7
• CD4 cell count with percentage (primary marker of immune function and disease progression) 5, 7
• Genotypic resistance testing to assess for transmitted drug resistance, even if therapy is deferred 7
• HLA-B*5701 testing before initiating abacavir to identify hypersensitivity risk 7
• Coreceptor tropism assay if CCR5 antagonist use is being considered 7

Safety Monitoring:

• Complete blood count with differential 7
• Comprehensive metabolic panel (liver enzymes, bilirubin, albumin, electrolytes, BUN, creatinine) 7
• Fasting glucose/HbA1c and lipid profile 7
• Urinalysis and calculated creatinine clearance (especially for Black patients and those with advanced disease) 7
• G6PD screening for patients with predisposing racial/ethnic backgrounds 7

Coinfection Screening:

• Tuberculosis screening (TST or IGRA) 7
• Hepatitis B (HBsAg, HBsAb, anti-HBc) and hepatitis C antibody 7
• Syphilis serology 5, 7
• Toxoplasma gondii IgG 7
• For females: N. gonorrhoeae, C. trachomatis, Pap smear, wet mount 5
• Chest radiography if positive TB test or underlying lung disease 7

Important Note: The CD4 cell count is used to stage HIV disease, determine risk of complications, and guide prophylaxis decisions. CD4 counts of 200 and 500 cells/mm³ generally correspond to CD4 percentages of 14% and 29%, respectively. 5

Treatment Initiation

Immediate Antiretroviral Therapy

All persons diagnosed with HIV should be offered ART immediately upon diagnosis, regardless of CD4 count or viral load. 1, 2

• Preferred regimens include an integrase strand transfer inhibitor (INSTI) plus two nucleoside reverse transcriptase inhibitors (NRTIs). 2
• Do not delay treatment while awaiting baseline laboratory results if patient is ready to start. 1, 2

Monitoring During Treatment

Viral Load Monitoring

• Measure at 4-6 weeks after starting or changing ART regimen to assess initial response. 1, 2
• Measure every 3 months until HIV RNA <50 copies/mL for at least 1 year. 1
• After achieving 1 year of viral suppression with consistent adherence, measure every 6 months. 1

CD4 Count Monitoring

• Measure every 6 months until counts are >250/μL for at least 1 year with concomitant viral suppression. 1, 2
• CD4 monitoring can be discontinued once this threshold is maintained. 1

Psychosocial and Behavioral Support

Immediate Counseling Needs

• Patients typically experience emotional distress when first informed of positive HIV test results. 5
• Behavioral and psychosocial services are integral to HIV care and should be available on-site or through referral. 1, 2
• Routine screening and treatment for depression is recommended for all HIV-infected patients. 1, 2

Partner Notification

• Strongly encourage patients to disclose HIV status to spouses, current sex partners, and previous sex partners. 5
• Health departments can assist with partner notification without disclosing the patient's identity. 5

Prevention Counseling

• Post-exposure prophylaxis (PEP) should be offered to persons with high-risk exposure within the previous 72 hours. 1
• Pre-exposure prophylaxis (PrEP) should be offered to HIV-negative persons with ongoing high risk for HIV infection. 1, 2

Critical Pitfalls to Avoid

• Never rely solely on patient-reported risk behaviors, as many infected individuals either don't recognize their risk or won't disclose behaviors. 1
• Never delay testing in low-prevalence settings, as screening is cost-effective even at prevalence as low as 0.1-0.2%. 1
• Never establish HIV diagnosis without confirmatory testing, as false-positive screening results can occur. 5, 1, 2
• Never delay ART initiation once diagnosis is confirmed, regardless of CD4 count. 1, 2