Table 4 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 2

 It’s easy to forget asthma medicine.

0.886

0.192

0.017

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

0.829

0.340

-0.096

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

0.820

0.350

-0.014

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

0.678

0.150

0.293

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

0.606

0.441

0.148

 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.

0.260

0.889

0.038

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

0.287

0.877

0.011

 I don’t follow the doctor’s prescription of asthma medicine exactly but instead I can feel how much I need to take.

0.333

0.861

0.048

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

0.039

0.049

0.959

 I worry about the side-effects of asthma medicine.

0.081

0.018

0.956