Asthma increase among farmers: a 12-year follow-up

Figures & data

Figure 1. Obstructive symptoms population estimates in 1982 and 1994.

Figure 2. Obstructive symptoms population estimates in the whole cohort in 1982 compared to the obstructive symptoms in 1982 in the 36 farmers with asthma 1994.

Figure 3. Prevalence of asthma in farmers compared to the general population.

Table I. Characteristics of the interviewed farmers in diagnostic groups.

Diagnosis		Doctor-diagnosed asthma		Chronic bronchitis		Inhalation fever (ODTS)		No respiratory symptoms		All
Number	n	36		27		29		117		270
Sex	Women/Men	7/36	19%	7/27	26%	1/29	3%	16/117	14%	36/270	13%
Age years	mean (SD)	59	±11	56	±10	55	±11	55	±11	56	±11
Smokers	n, %	3	6%	6^a	22%	2	7%	13	11%	26	10%
Ex-smokers	n, %	14	44%	6	19%	9	30%	26	22%	74	27%
Never smokers	n, %	19	50%	15	59%	18	63%	78	67%	170	63%

^a P < 0.01.

ODTS = Organic Dust Toxic Syndrome.

Table II. Results of the pulmonary function test in different diagnostic groups.

Diagnosis		Doctor-diagnosed asthma		Chronic bronchitis		Inhalation fever (ODTS)		No respiratory symptoms		All
FEV1, %, predicted 1982	mean (SD)	93^b	±15	98	±15	100	±9	104	±14	100^b	±15
FEV1, %, predicted 1994	mean (SD)	82^c	±21	91^b	±19	93	±13	98	±15	94^b	±17
FEV1 loss 1982–1994, %, of predicted value	mean (SD)	11^a	±16	8	±9	7	±8	5	±8	6	11
FEV1 loss 1982–1994 mean annual losses, mL; Men	mean (SD)	60^a	±49	53	±24	47	±31	45	±27	47	±32
FVC, %, predicted 1982	mean (SD)	94	±12	95	±16	93^a	±9	100	±14	97^b	±13
FVC, %, predicted 1994	mean (SD)	85^b	±13	90^a	±16	89^a	±11	95	±14	92^b	±14
FVC loss 1982–1994, %, of predicted value	mean (SD)	8	±12	4	±6	5	±6	5	±6	5	±8
FVC loss 1982–1994, mean annual losses, mL; Men	mean (SD)	59^a	±48	40	±29	37	±36	43	±30	44	±34

^a P < 0.05.

^b P < 0.01.

^c P < 0.001.

FEV1 = Forced Expiratory Volume in 1 second; FVC = Forced Expiratory Volume in 1 second; ODTS = Organic Dust Toxic Syndrome.

Table III. Results of allergy and precipitins tests in different diagnostic groups.

Diagnosis		Doctor-diagnosed asthma		Chronic bronchitis		Inhalation fever (ODTS)		No respiratory symptoms		All
Phadiatop +	n, %	5^a	14%	3	11%	3	10%	4	3%	18	7%
RAST storage mites +	n, %	3	8%	0	0%	3	10%	3	3%	7	3%
Phadiatop + or RAST storage mites +	n, %	8^b	23%	3	11%	4	13%	6	5%	25	9%
RAST cow dander +	n, %	3	8%
Allergy tests + (Phadiatop+ or any RAST+)	n, %	10	28%
Total IgE	mean (SD)	147^c	±239	40	±39	63	±115	48	±77	60	±114
ECP mg/L	mean (SD)	10.9	±6.0	11.0	±6.7	8.6	±4.8	9.6	±5.4	10.0	±5.6
Precipitins(+), +, and ++	n, %	4	11%	2	7%	8	27%	23	20%	48	18%

^a P < 0.05.

^b P < 0.01.

^c P < 0.001.

ODTS = Organic Dust Toxic Syndrome; ECP = Eosinophil cationic protein.

Table IV. IgE-mediated asthma compared to non-IgE-mediated asthma.

	Doctor-diagnosed asthma 1994
Obstructive symptoms 1982	Allergy test positive 1994	Allergy test negative 1994
No symptoms	1	10
Wheeze colds	1	9
Definite wheeze	0	4
Asthma	6	4
Total	8	27