History and exam
Key diagnostic factors
common
presence of risk factors
Key risk factors include exposure to infection, immunosuppression, silicosis, malignancy, birth in an endemic country, and HIV in appropriate areas.
cough
Duration over 2 to 3 weeks; initially dry, later productive. Outpatient study found that only 50% of patients had cough over 2 weeks.[50]
fever
Fever is usually low-grade. Up to 20% of patients may have no fever. Fever is less common in older people.
anorexia
May be seen in patients with other suggestive symptoms.
weight loss
May be seen in patients with other suggestive symptoms.
malaise
May only be noticed in hindsight, after treatment.
Other diagnostic factors
common
night sweats
If present; usually drenching.
uncommon
pleuritic chest pain
May suggest pleuritic involvement.
haemoptysis
Present in <10% of patients (typically with advanced disease). May be the result of sequelae (e.g., bronchiectasis) and not represent active disease.
psychological symptoms
May include depression or hypomania.
abnormal chest auscultation
Chest examination may be normal in mild/moderate disease. Possible findings include crackles, bronchial breath sounds, or amphoric breath sounds (distant hollow breath sounds heard over cavities).
asymptomatic
Patient may be asymptomatic and diagnosis made from coincidental findings or screening.
dyspnoea
A late finding in the setting of extensive lung destruction or effusion.
clubbing
Only in long-standing disease.
erythema nodosum and erythema induratum
Painful raised erythematous nodules over pretibial region or on the calves.
Risk factors
strong
exposure to infection
This is necessary but not sufficient for development of TB. Among household contacts, approximately one third acquire latent TB infection and 1% to 2% are found to have active TB disease. People with recently acquired infection (e.g., tuberculin skin test conversion within the past 2 years) have a greatly increased risk of developing active TB.[11][12]
birth in an endemic country
High-risk regions include Asia, Latin America, and Africa.[13]
HIV infection
Increases the risk for both progression to primary disease and re-activation of latent disease. The risk for re-activation in an HIV-positive patient with latent infection is up to 10% per year, as opposed to 10% lifetime risk in HIV-negative patients. In addition, active TB has been found to increase HIV viral loads.[14][15][16][17]
immunosuppressive medicines
Especially systemic corticosteroids and tumour necrosis factor-alpha antagonists. Risk with steroids increases with increasing doses (odds ratio 7.7 for >15 mg/day of prednisone) and varies with underlying condition. The risk with infliximab is greater than with etanercept. Relative risk following organ transplantation is 20- to 74-fold greater.[18][19]
silicosis
30 times increased risk compared with controls.[21]
apical fibrosis
Patients whose chest x-ray shows upper lobe fibrotic opacities consistent with prior untreated pulmonary TB are at greater risk for developing active disease (estimated risk ≥0.3% per year, depending on the size of radiographic abnormalities).[22]
weak
malignancy
Risk is increased in patients with haematological malignancy and head and neck cancer. However, US-born patients with other solid tumours do not appear to be at higher risk of progression to active TB.[20]
end-stage renal disease
Patients on haemodialysis are at increased risk.
intravenous drug use
Increases risk, even without HIV infection.[12]
malnutrition
Includes people with low body weight (<90% of ideal body weight), coeliac disease, and history of gastrectomy. Risk is also greater in patients with jejunoileal bypass.
alcoholism
Hard to separate from other risk factors.
diabetes
The estimated global prevalence of diabetes among patients with pulmonary TB in one meta-analysis was 13.73%.[23]
high-risk congregate settings
Residents or employees of correctional facilities, homeless shelters, or nursing homes are at increased risk.
low socio-economic status or black/Hispanic/Native American ancestry
Multivariate models suggest at least half the risk attributed to ethnicity (black, Hispanic, Native American) may be the result of low socio-economic status.[24]
age
Both the very young (age <5 years) and older people are at increased risk for progression to disease.
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