Table S1.
Rotated factor loadings of IMB items: 3-factor solution
| IMB constructs | Survey items | Factor loadings
|
||
|---|---|---|---|---|
| Factor 1 | Factor 2 | Factor 3 | ||
| Information | I know what the possible side effects of each of my vasculitis medicines are | −0.032 | 0.006 | 0.736 |
| I understand how each of my vasculitis medicines works in my body to fight vasculitis | 0.005 | 0.003 | 0.721 | |
| I know how each of my vasculitis medicines is supposed to be taken | −0.019 | 0.129 | 0.692 | |
| I know what to do if I miss a dose of my vasculitis medicines | −0.062 | 0.087 | 0.645 | |
| I believe that if I take my vasculitis medicines as prescribed, I will live longer | 0.032 | 0.020 | 0.491 | |
| If I do not take my vasculitis medicines as prescribed, these kinds of medicines may not work for me in the future | 0.039 | −0.074 | 0.356 | |
| As long as I am feeling healthy, missing my vasculitis medicines from time to time is OKa | 0.369 | −0.187 | 0.247 | |
| Skipping a few of my vasculitis medicines from time to time would not really hurt my healtha | 0.432 | −0.237 | 0.173 | |
| I believe that my vasculitis medications do not interact with alcohola | 0.048 | 0.253 | −0.378 | |
| Motivation | It upsets me that the vasculitis medicines I have been prescribed can cause side effects | −0.120 | 0.834 | −0.027 |
| It upsets me that the vasculitis medicines I have been prescribed can affect the way I look | −0.059 | 0.810 | −0.057 | |
| I am worried that the vasculitis medicines I have been prescribed will hurt my health | −0.109 | 0.776 | 0.076 | |
| It frustrates me to think that I will have to take these medicines for the rest of my life | 0.012 | 0.665 | 0.013 | |
| I get frustrated taking my vasculitis medicines because I have to plan my life around them | 0.129 | 0.607 | −0.024 | |
| I do not like taking my vasculitis medicines because they remind me that I have vasculitis | 0.137 | 0.533 | 0.022 | |
| I am worried that other people might realize that I have a disease if they see me taking my vasculitis medicinesa | 0.166 | 0.247 | −0.002 | |
| Behavioral | How hard or easy is it for you to take vasculitis medicines when you do not feel good emotionally? | 0.872 | 0.112 | −0.104 |
| How hard or easy is it for you to make vasculitis medicines part of your daily life? | 0.867 | −0.002 | −0.038 | |
| How hard or easy is it for you to take your vasculitis medicines when you are wrapped up in what you are doing? | 0.827 | −0.083 | −0.022 | |
| How hard or easy is it for you to remember to take your vasculitis medicines? | 0.802 | −0.079 | 0.023 | |
| How hard or easy is it for you to take your vasculitis medicines when your usual routine changes? | 0.788 | −0.006 | 0.001 | |
| How hard or easy is it for you to take your vasculitis medicines when you do not feel good physically? | 0.773 | 0.110 | −0.198 | |
| How hard or easy is it for you to take your vasculitis medicines when you feel good physically? | 0.757 | 0.012 | 0.007 | |
| How hard or easy is it for you to manage the side effects of your vasculitis medicines? | 0.658 | 0.087 | −0.087 | |
| How hard or easy is it for you to talk to your health care provider about your vasculitis medicines? | 0.481 | 0.204 | 0.078 | |
| How hard or easy is it for you to get your vasculitis medicines refilled on time? | 0.552 | −0.066 | 0.153 | |
| How hard or easy is it for you to stay informed about your vasculitis treatment?a | 0.394 | 0.105 | 0.339 | |
| How hard or easy is it for you to get the support you need from others for taking your vasculitis medicines?a | 0.295 | 0.162 | 0.308 | |
Notes: “There are times when it is hard for me to take my vasculitis medications when I drink alcohol or use street drugs” was omitted from the behavioral scale based on cognitive interviews with vasculitis patients. “How hard or easy is it for you to take your vasculitis medications because the pills are hard to swallow, taste bad, or make you sick to your stomach” was omitted from the behavioral scale based on cognitive interviews with vasculitis patients. Possible score range =1–5, higher scores indicate greater adherence.
a
Items that were omitted for poor loadings or cross loadings in red.
Abbreviation: IMB, information–motivation–behavioral skills.