Table 3 Factor loadings from Principal component analysis with Varimax and Kaiser normalization as the rotation method for the final three-factor solution and Cronbach’s α in phase 1

 It’s easy to forget asthma medicine.

0.842

-0.018

0.027

 I don’t have any real habits for my asthma medicine but instead I take them when I remember to.

0.794

0.243

-0.089

 I’m like a periodical drinker as far as my asthma medicine is concerned.

0.723

0.252

0.011

 Sometimes I test going without my asthma medicine to see what it’s like.

0.627

0.303

0.085

 I don’t use my asthma medicine exactly like my doctor has said.

0.500

0.458

0.305

 I don’t really follow the instructions for my asthma medicine but instead I can feel what my body needs. If I feel I need more, I take more. If I feel I need less, I take less.

0.182

0.900

0.047

 I can tell myself how I feel and how much of my asthma medicine I need to take.

0.132

0.779

-0.188

 I don’t follow the doctor’s prescription exactly but instead I can feel what I need to take.

0.275

0.698

0.086

 I’m worried about how my asthma medicine will affect my body in the long run.

0.009

-0.034

0.949

 I worry about the side-effects of asthma medicine.

0.036

0.016

0.957