Chronic Cough, Tuberculosis, and Lung Cancer

Learning Objectives

• Classify cough by duration and apply a systematic approach to chronic cough (>8 weeks)
• Identify the 'big three' causes of chronic cough with a normal CXR in non-smokers
• Recognise red flags for chronic cough in children and adults
• Assess hemoptysis severity and determine when to refer urgently
• Differentiate latent from active TB and apply Singapore's notification and treatment protocols
• Identify high-risk groups for lung cancer and apply current screening criteria

The 'Big Three' — Chronic Cough with Normal CXR

• In non-smokers with a normal chest X-ray, the top three causes are:
• ① UACS (Upper Airway Cough Syndrome) — postnasal drip, rhinitis, sinusitis → trial antihistamine + decongestant
• ② Asthma / Cough-Variant Asthma — nocturnal, worse with irritants → spirometry, trial ICS 2–4 weeks
• ③ GERD — may be 'silent' in up to 75% (no typical heartburn) → empirical PPI trial
• Eosinophilic bronchitis: non-productive cough without asthma features → also responds to ICS
• Empirical sequential trials are acceptable when initial CXR is normal and no red flags

Pneumothorax — Diagnosis and Management

• PSP: young, tall, slender, smoker — no underlying lung disease
• SSP: underlying lung disease (COPD, asthma, TB) — worse prognosis
• Tension pneumothorax: respiratory distress, tachycardia, hypotension, tracheal deviation — EMERGENCY
• Asymptomatic/minimal: conservative management regardless of size
• Symptomatic: refer A&E for needle aspiration or chest drain
• Tension: immediate needle decompression — 2nd ICS MCL (traditional) OR 4th/5th ICS anterior axillary line (ATLS 10th ed. — preferred if thick chest wall)

Hemoptysis — Assessment and Triage

Tuberculosis in Singapore

• Incidence: 28.9 per 100,000 in 2023 — TB remains endemic in Singapore
• High-risk groups: elderly, immunocompromised, migrants, diabetes mellitus, HIV
• Airborne transmission: maintain high index of suspicion for cough >3 weeks + constitutional symptoms
• Pulmonary TB: most common — cough, haemoptysis, fever, night sweats, weight loss
• Extrapulmonary TB: lymph nodes, pleura, bones, meninges — more common in immunosuppressed
• Screen all TB patients for HIV and diabetes mellitus

TB Diagnosis and Treatment

• Active TB: sputum AFB smear + culture; CXR shows upper lobe infiltrates, cavities
• LTBI: TST (≥10 mm general; ≥5 mm immunocompromised) or IGRA
• Active TB treatment (drug-susceptible): RIPE × 2 months → RI × 4 months
• LTBI treatment (Singapore 2024 guidelines): Rifampicin daily × 4 months (preferred) OR INH × 6–9 months
• Extend to 9 months if: cavitation, positive 2-month culture, slow response, significant comorbidities
• DOT/VOT is a cornerstone of Singapore's TB control programme

TB — Public Health Obligations

Lung Cancer — Epidemiology and Risk Groups

• 3rd most common cancer in Singapore (2017–2021); leading cause of cancer death in men
• NSCLC ~80% (adenocarcinoma, squamous cell, large cell); SCLC ~20%
• Key risk groups in Asia — beyond smokers:
• • Never-smoker, Female, East Asian (NESFEA) phenotype — often adenocarcinoma with EGFR mutations
• • Family history of lung cancer
• • Exposure to carcinogens: radon, asbestos, air pollution
• Family physicians play a key role in early suspicion and smoking cessation

Lung Cancer Screening and Solitary Pulmonary Nodule

• No national screening programme in Singapore — MOH recommends LDCT on individual basis for high-risk patients
• USPSTF 2021 criteria (reference benchmark): Annual LDCT for adults aged 50–80 with ≥20 pack-year history, currently smoking or quit within 15 years
• Solitary pulmonary nodule (SPN): isolated opacity <3 cm — most are benign (infectious granuloma 80%)
• Features suggesting malignancy: size ≥8 mm, spiculated border, upper lobe, ground-glass opacity, eccentric calcification
• Features suggesting benign: smooth border, central/popcorn calcification, doubling time <1 month or >1 year
• Refer to respiratory physician for all SPNs — risk stratification guides follow-up imaging frequency