Determinants of persistent asthma in young adults

Figures & data

Table 1. Characteristics of the asthmatic individuals and unadjusted associations of baseline determinants (OR) with persistent asthma and COPD at follow up.

		Diagnosis at follow up
	Asthma at baseline (n = 239)	Persistent asthma (n = 164)		COPD (n = 35)
Determinants, baseline	n (%)	n (%)	OR (95%CI)	n (%)	OR (95%CI)
Sex, female	150 (62.8%)	99 (60.4%)	0.72 (0.38–1.32)	22 (62.9%)	1.00 (0.45–2.31)
Age ≥35 years	122 (51.1%)	80 (48.8%)	0.75 (0.42–1.34)	22 (62.9%)	1.76 (0.80–4.01)
Age of onset ≥16 years^a	119 (55.6%)	81 (52.3%)	0.60 (0.31–1.17)	15 (48.4%)	0.71 (0.31–1.64)
Bronchial hyperresponsiveness^b	95 (39.8%)	65 (39.6%)	1.11 (0.60–2.07)	14 (40.0%)	1.81 (0.71–4.81)
Atopy	146 (61.1%)	104 (63.4%)	1.36 (0.75–2.46)	17 (48.6%)	0.55 (0.25–1.21)
FEV₁ below pred	191 (79.9%)	139 (84.8%)	2.46 (1.21–4.95)	33 (94.3%)	4.80 (1.15–42.65)
ACOS	46 (19.3%)	39 (23.8%)	3.03 (1.25–8.43)	19 (54.3%)	7.78 (3.31–18.23)
Medication, 12 mth
SABA only	63 (26.4%)	48 (29.3%)	5.06 (2.43–10.54)	8 (22.9%)	1.15 (0.42–3.17)
ICS and/or LABA	96 (40.2%)	85 (51.8%)	12.21 (5.64–26.45)	18 (51.4%)	1.82 (0.77–4.31)
Asthma Score^c			1.48 (1.20–1.82)		1.16 (0.91–1.48)
BMI >30 kg^gm^−2^d	46 (19.3%)	31 (19.0%)	0.94 (0.45–2.02)	5 (14.3%)	0.66 (0.19–1.87)
Nasal allergy	168 (70.3%)	122 (74.4%)	1.83 (0.98–3.41)	22 (62.9%)	0.67 (0.30–1.56)
Parental asthma	92 (38.5%)	67 (40.9%)	1.38 (0.75–2.57)	13 (37.1%)	0.93 (0.41–2.07)
Current smoking	68 (28.5%)	37 (22.6%)	0.41 (0.22–0.78)	14 (40.0%)	1.85 (0.81–4.13)
High-risk occupation (asthma)^e	119 (50.4%)	81 (50.0%)	0.95 (0.53–1.70)	15 (42.9%)	0.70 (0.31–1.53)
High-risk occupation (COPD)^f	126 (53.4%)	85 (52.5%)	0.89 (0.49–1.60)	16 (45.7%)	0.70 (0.32–1.52)
White collar work^g	153 (64.6%)	103 (63.2%)	0.70 (0.32–1.47)	22 (62.9%)	0.76 (0.31–1.93)
Blue collar work^g	55 (23.2%)	41 (25.2%)	1.42 (0.68–3.09)	10 (28.6%)	1.32 (0.52–3.18)
Respiratory infection <5 years of age	30 (12.6%)	23 (14.0%)	1.58 (0.62–4.58)	8 (22.9%)	2.45 (0.85–6.43)
Mould inside the home	85 (35.6%)	57 (34.8%)	0.89 (0.49–1.65)	15 (42.9%)	1.44 (0.64–3.15)

Bold values denote significant associations (p < 0.05).

^an = 214; 25 participants missing in variable ‘age at onset’.

^bn = 210; 29 missing i.e. did not receive methacholine challenge test

^cAsthma score as a continuous variable.

^dn = 238; 1 participant missing in variable BMI.

^en = 236; 3 participants missing in variable ‘high-risk occupation (asthma)’.

^fn = 236; 3 participants missing in variable ‘high-risk occupation (COPD)’.

^gn = 208; 2 participants missing, 29 unclassifiable.

The table shows odds ratios (OR) with 95% confidence intervals (95% CI).

Figure 1. The distribution of asthma score at baseline (green) and follow up (red) and the percentage of individuals in each group reporting use of medication for breathing within the last 12 months by asthma score at baseline and follow up, respectively.

Table 2. Determinants for persistent asthma and COPD at follow up by logistic regression in 239 individuals with asthma at baseline.

	Follow up
	Persistent asthma, OR (95%CI)			COPD, OR (95%CI)
Determinants, Baseline	All (n = 164)	Early-onset asthma (n = 74)^a	Late-onset asthma (n = 81)^a	All (n = 35)	Early-onset asthma (n = 16)^b	Late-onset asthma (n = 15)^b
Sex, female	0.70 (0.35–1.40)	0.69 (0.17–2.83)	0.70 (0.26–1.84)	1.43 (0.61–3.38)	20.40 (1.57–265.69)	0.71 (0.15–3.33)
FEV₁ below pred	2.12 (0.98–4.61)	7.12 (1.61–31.50)	1.53 (0.53–4.40)	3.05 (0.67–13.91)	2.91 (0.23–37.35)	NA
Bronchial hyperresponsiveness	1.01 (0.51–2.00)	2.18 (0.36–13.21)	1.13 (0.43–2.97)	0.79 (0.35–1.81)	0.06 (0.01–0.56)	3.04 (0.68–13.70)
ACOS	2.60 (0.89–7.62)	2.81 (0.23–34.00)	1.27 (0.29–5.63)	6.98 (2.84–17.14)	204.96 (9.20–4566.65)	15.53 (3.22–74.76)
Asthma Score per step increase.	1.21 (0.94–1.56)	2.06 (1.15–3.68)	1.12 (0.80–1.56)	1.03 (0.78–1.37)	1.39 (0.81–2.39)	0.84 (0.52–1.34)
Medication, 12 mth
SABA only	3.39 (1.47–7.82)	4.52 (0.81–25.22)	2.26 (0.69–7.42)	0.90 (0.27–2.99)	5.06 (0.60–42.67)	0.25 (0.02–2.84)
ICS and/or LABA	8.95 (3.87–20.69)	9.87 (1.95–49.98)	6.84 (2.09–22.37)	1.22 (0.41–3.59)	0.38 (0.05–3.19)	1.29 (0.19–8.67)
Current smoking	0.45 (0.21–0.94)	1.01 (0.20–5.15)	0.98 (0.35–2.72)	1.86 (0.74–4.70)	4.54 (0.67–30.53)	2.25 (0.51–10.00)
High-risk occupation (asthma) ^c	2.48 (0.45–13.72)	1.18 (0.04–33.77)	1.97 (0.26–14.90)	0.35 (0.03–3.59)	NA	0.08 (0.00–2.33)
High-risk occupation (COPD)^d	0.53 (0.10–2.87)	1.25 (0.04–36.31)	0.57 (0.08–4.15)	1.93 (0.20–18.83)	NA	7.78 (0.31–197.17)

Bold values denote significant associations (p < 0.05).

^an (total) = 155 due to missing data on age at first asthma attack.

^bn (total) = 31 due to missing data on age at first asthma attack.

^cn = 236; 3 participants had missing in variable ‘high-risk occupation (asthma)’.

^dn = 236; 3 participants had missing in variable ‘high-risk occupation (COPD)’.

NA: Not applicable

The table shows odds ratios (OR) with 95% confidence intervals (95% CI).

Table 3. Association between baseline determinants and asthma score at follow up (OR per step increase), FEV₁ at baseline and FEV₁ at follow up (coeff.).

	Asthma score at follow up	FEV₁ at baseline (liter)	FEV₁ at follow up (liter)
Determinants, baseline	OR (95%CI)	Coefficient (95%CI)	Coefficient (95%CI)
Sex, female	1.07 (0.65–1.74)	−1.006 (−1.144−0.868)	0.050 (−0.050–0.151)
FEV₁	–	–	1.026 (0.958–1.095)
FEV₁ below pred.	1.44 (0.78–2.66)	–	–
Bronchial hyperresponsiveness	1.37 (0.84–2.23)	−0.014 (−0.149–0.121)	−0.004 (−0.075–0.068)
ACOS	1.66 (0.88–3.11)	−0.398 (−0.576−0.221)	0.025 (−0.072–0.123)
Asthma Score per step increase	1.60 (1.34–1.91)	0.007 (−0.042–0.055)	−0.001 (−0.027–0.024)
Medication, 12 mth
SABA only	1.50 (0.77–2.94)	0.046 (−0.138–0.231)	0.099 (0.002–0.196)
ICS and/or LABA	1.14 (0.63–2.08)	0.005 (−0.162–0.172)	0.029 (−0.059–0.117)
Current smoking	0.89 (0.51–1.57)	−0.141 (−0.295–0.014)	0.020 (−0.062–0.102)
High-risk occupation (asthma)^a	1.16 (0.31–4.28)	0.133 (−0.266–0.531)	0.076 (−0.134–0.285)
High-risk occupation (COPD) ^b	1.26 (0.34–4.68)	−0.047 (−0.444–0.350)	−0.042 (−0.250–0.167)

Bold values denote significant associations (p < 0.05).

^an = 236; 3 participants had missing in variable ‘high-risk occupation (asthma)’.

^bn = 236; 3 participants had missing in variable ‘high-risk occupation (COPD)’.

Regarding FEV₁ negative numbers report larger decrease. The table shows odds ratios (OR) and regression coefficients with 95% confidence intervals (95% CI).