Low cholesterol levels are associated with higher death rates from respiratory diseases

This study was published in the International Journal of Epidemiology 1997 Dec;26(6):1191-202

Study title and authors:
Serum total cholesterol and risk of hospitalization, and death from respiratory disease.

Iribarren C, Jacobs DR Jr, Sidney S, Claxton AJ, Gross MD, Sadler M, Blackburn H.
Division of Research, Kaiser Permanente Medical Care Program, Oakland, CA 94611, USA.

This study can be accessed at: http://www.ncbi.nlm.nih.gov/pubmed/9447398

The study examined the association of cholesterol levels with respiratory diseases. The study included 48,188 men, 55,276 women, age range 25-89, who were followed for 15 years with a total of 976,866 person years of observation.

The study found for patients requiring hospitalisation:
(a) Those with the lowest cholesterol levels, below 4.14 mmol/L (160 mg/dL), had a 41% increased risk of been hospitalised with pneumonia and influenza compared with those with the highest cholesterol levels, above 6.2 mmol/L (240 mg/dL).
(b) Those with the lowest cholesterol levels, below 4.14 mmol/L (160 mg/dL), had a 17% increased risk of been hospitalised with chronic obstructive pulmonary disease (bronchitis and emphysema) compared with those with the highest cholesterol levels, above 6.2 mmol/L (240 mg/dL).
(c) Those with the lowest cholesterol levels, below 4.14 mmol/L (160 mg/dL), had a 13% increased risk of been hospitalised with asthma compared with those with the highest cholesterol levels, above 6.2 mmol/L (240 mg/dL).
(d) Those with the lowest cholesterol levels, below 4.14 mmol/L (160 mg/dL), had a 35% increased risk of been hospitalised with other respiratory diseases (rhinitis, sinusitis, tonsilitis, laringitis, asbestosis, pneumuconiosis, empyema, mediastinitis, pleurisy, pulmonary congestion, pulmonary fibrosis, rhumatic pneumonia and lung disease) compared with those with the highest cholesterol levels, above 6.2 mmol/L (240 mg/dL).

With regard to death from respiratory diseases the study found:
(e) Men with the lowest cholesterol levels, below 4.14 mmol/L (160 mg/dL), had a 87% increased risk of death from pneumonia and influenza compared with men with the highest cholesterol levels, above 6.2 mmol/L (240 mg/dL).
(f) Women with the lowest cholesterol levels, below 4.14 mmol/L (160 mg/dL), had a 41% increased risk of death from pneumonia and influenza compared with women with the highest cholesterol levels, above 6.2 mmol/L (240 mg/dL).
(g) Men with the lowest cholesterol levels, below 4.14 mmol/L (160 mg/dL), had a 35% increased risk of death from bronchitis, emphysema and asthma compared with men with the highest cholesterol levels, above 6.2 mmol/L (240 mg/dL).
(h) Women with the lowest cholesterol levels, below 4.14 mmol/L (160 mg/dL), had a 79% increased risk of death from bronchitis, emphysema and asthma compared with women with the highest cholesterol levels, above 6.2 mmol/L (240 mg/dL).
(i) Men with the lowest cholesterol levels, below 4.14 mmol/L (160 mg/dL), had a 96% increased risk of death from other respiratory diseases (rhinitis, sinusitis, tonsilitis, laringitis, asbestosis, pneumuconiosis, empyema, mediastinitis, pleurisy, pulmonary congestion, pulmonary fibrosis, rhumatic pneumonia and lung disease) compared with men with the highest cholesterol levels, above 6.2 mmol/L (240 mg/dL).
(j) Women with the lowest cholesterol levels, below 4.14 mmol/L (160 mg/dL), had a 126% increased risk of death from other respiratory diseases (rhinitis, sinusitis, tonsilitis, laringitis, asbestosis, pneumuconiosis, empyema, mediastinitis, pleurisy, pulmonary congestion, pulmonary fibrosis, rhumatic pneumonia and lung disease) compared with women with the highest cholesterol levels, above 6.2 mmol/L (240 mg/dL).

The results of the study show that low cholesterol levels are associated with more hospitalisations and higher death rates from respiratory diseases.