Risk factors for ILDs

There are a number of risk factors for the development of ILD that should prompt suspicion of pulmonary fibrosis1,2

ILD patients with the HRCT scans in their hands.


IPF typically occurs between 60 and 70 years of age,2,4 but older age brings greater risk of IPF3

  • Age ≥70 years: 95% positive predictive value for IPF

  • Age ≥75 years: ~100% positive predictive value for IPF

In a study of 920 patients with IPF, 62% were men5

There is a strong association between smoking and IPF, especially for those with a greater than 20 pack-years history6

A number of environmental and occupational exposures have been associated with increased risk for IPF, including silica, sand or stone7,8

Risk factors for development of IPF


  • Old age2

  • 60–70 years1,4



  • Smoking6

  • Silica, sand, stone7

  • Livestock/farming8

Other conditions

  • GERD2

  • Epstein-Barr virus2

  • Hepatitis C2


  • Familial history2



iNSIP is characterized by an NSIP pattern on HRCT with no known cause. Risk factors for development of iNSIP include female sex and middle age,10 with the median age of onset being 52 years11

Male patient with fibrotic iNSIP


HP is characterized by pulmonary disease accompanied by systemic manifestations, such as fever or weight loss, and is caused by inhalation of an antigen to which the patient has been sensitized.12

Environmental antigens from occupations or hobbies associated with HP include activities involving birds, farming, cheese, fur and malt.13

Female patient with fibrotic cHP

What sources of environmental antigens are associated with HP?

Sources of environmental antigens associated with HP12


  • Moldy hay and grain (farmer’s lung)


  • Moldy hay and grain (farmer’s lung)

  • Moldy compost and mushrooms (mushroom worker’s lung)

  • Contaminated houses (Japanese summer-type HP)

  • Moldy cork (suberosis)

  • Moldy cheese or cheese casings (cheese washer’s lung)

  • Contaminated wood pulp or dust (woodworker’s lung)


  • Mold on ceiling; tub water (hot tub lung)

  • Mist from pool water, sprays and fountains (swimming pool lung)

Animal proteins

  • Proteins in avian droppings and serum on feathers (pigeon breeder’s lung; bird fancier’s lung)

  • Avian proteins in feather beds, pillows and duvets (feather duvet lung)

  • Silkworm proteins in dust from silkworm larvae and cocoons (silk production HP)


  • Diisocyanates and trimellitic anyhydride from polyurethane foams, spray paints, dyes and glues (chemical worker’s lung)


Sarcoidosis-associated interstitial lung disease is the pulmonary manifestation of a multisystem granulomatous disease of unknown cause that primarily affects the respiratory and lymphatic systems.14

Female patient with sarcoidosis-associated interstitial lung disease

What are the risk factors for the development of sarcoidosis-associated interstitial lung disease?

Risk factors for development of sarcoidosis-associated interstitial lung disease


20–40 years14–16




African American14


Familial clustering14,15


SSc-ILD is the pulmonary manifestation of a systemic autoimmune disease that affects multiple organs, including the skin. Risk of developing ILD in patients with SSc is higher in those who are:18–22

  • >65 years old

  • Male

  • African or Native American heritage

  • Diagnosed with diffuse cutaneous systemic sclerosis (dcSSc)

  • Smoking or have a history of smoking

  • Serologically positive for anti-topoisomerase I antibody


RA-ILD is the pulmonary manifestation of a systemic autoimmune disease that affects the joints. Risk of developing ILD in RA patients is higher in those who are:23–33 

  • >65 years old

  • Male

  • Experiencing longer disease duration or higher disease activity 

  • Smoking or have a history of smoking

  • Serologically positive for RF or anti-CCP antibody

What should you consider after identifying risk factors for fibrotic ILDs in your patients?

  • Anti-CCP, anti–citrullinated protein antibody; dsSSc, diffuse cutaneous systemic sclerosis; GERD, gastroesophageal reflux disease; HP, hypersensitivity pneumonitis; HRCT, high-resolution computed tomography; ILD, interstitial lung disease; iNSIP, idiopathic non-specific interstitial; IPF, idiopathic pulmonary fibrosis; NSIP, non-specific interstitial pneumonia; RA, rheumatoid arthritis; RA-ILD, rheumatoid arthritis-associated interstitial lung disease; RF, rheumatoid factor; SSc, systemic sclerosis; SSc-ILD, systemic sclerosis-associated interstitial lung disease.

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