Smoking remains the leading cause of preventable death and disability in the U.S. with about 12.5 % of the population identifying as current smokers in 2020 (Cornelius, Loretan, Wang, Jamal, & Homa, 2022). Additionally, smoking rates are approximately 50 % higher in low income populations, such that the prevalence of cigarette use is 21.4 % among individuals earning <$35,000 per year compared to those with household incomes of $35,000–74,999 (15.7 %), $75,000–99,999 (11.4 %), and ≥$100,000 (7.1 %) (Cornelius, 2020). While there are several FDA-approved medications for smoking cessation, nicotine replacement therapy (NRT) remains one of the most widely available cessation products (Mersha, Eftekhari, Bovill, Tollosa, & Gould, 2020). NRT is available in multiple forms, including both long-acting and short-acting products, with many available over-the-counter (OTC) (Carpenter, Jardin, & Burris, 2013). Combination NRT (cNRT) is often suggested to supply a steady release of nicotine in a 24-hr period (with patch) while also providing a fast-acting product to address cravings (e.g., lozenge) (Cooney et al., 2009, Sweeney et al., 2001). Non-prescription NRTs are available in most drugstores and retail/grocery stores and are relatively inexpensive (Kishore, Bitton, Cravioto, & Yach, 2010). Therefore, individuals without a primary physician or health insurance may still obtain the most popular forms of NRT. These factors have made NRT a more accessible resource for low-income smokers (Dahne, Wahlquist, Smith, & Carpenter, 2020).

Despite these benefits of NRT, low adherence rates are a significant barrier to successful smoking cessation with NRT. Specifically, one large-scale international survey reported about 70 % of users prematurely quit use of NRTs (Balmford, Borland, Hammond, & Cummings, 2011). There are multiple cognitive factors unrelated to NRT products that affect adherence to NRT such as forgetfulness, self-efficacy for adherence, and motivation to quit, among others (Kim et al., 2019, Mersha et al., 2020, Ojo-Fati et al., 2016, Pacek et al., 2018). Specifically, higher motivation and self-efficacy for adherence are associated with a greater likelihood of adherence (Pacek et al., 2018). In one study examining adherence to the nicotine patch, motivation to quit smoking was associated with increased adherence and subsequently greater adherence also encouraged motivation (Shadel, Galvan, & Tucker, 2016). While interventions to increase medication adherence for smoking pharmacotherapies have had mixed success, building adherence self-efficacy is one way that has been suggested to address these issues (Shelley et al., 2015, Tseng et al., 2017). Additionally, depressive symptoms and negative mood are important factors that negatively impact smoking cessation success (Berlin and Covey, 2006, Leventhal et al., 2014) as well as adherence to treatment (Ojo-Fati et al., 2016, Webb et al., 2009). These variables and fluctuating factors could potentially impact NRT usage on a day-to-day basis, which may be further influenced by other variables such as income and gender.

Previous research suggests that women have worse smoking cessation outcomes than men, including higher risk of smoking-related morbidity and mortality (Allen et al., 2014, Kiyohara and Ohno, 2010). Numerous factors have been suggested to explain the differential smoking behaviors observed for women and men. For example, depressive mood, anxiety, anger, and perceived stress are predictors of time to relapse for women, but not men (Allen et al., 2014). Additionally, women smoke to cope with negative mood more often than men (Burgess, Fu, & Noorbaloochi, 2009). Moreover, men consistently report better adherence to smoking cessation medications (Pacek et al., 2018). In a meta-analysis of gender differences in cessation using nicotine patches, women had poorer responses to nicotine patches than men (Perkins & Scott, 2008). Nonetheless, women are more likely to seek assistance with quitting and use smoking cessation services (Jayakumar, Chaiton, Zhang, Selby, & Schwartz, 2020), so it is important to understand what specific factors impact their medication adherence in order to optimize treatment for them (Voci et al., 2021, Weinberger et al., 2014).

While extensive literature supports the broad impact of mood, motivation, and self-efficacy on NRT adherence, limited research has evaluated how these constructs differ by gender and how they change on a daily basis. Moreover, limited research has used daily assessments to measure NRT use, although daily assessments of NRT use are likely more accurate than standard measures of use because they limit recall bias associated with reporting on daily behaviors like nicotine patch use and short-acting NRT use (Hébert et al., 2021, Ma et al., 2016). This study is the first to examine the relationship between same-day negative mood, motivation, and self-efficacy in relation to daily NRT adherence, while also evaluating gender differences in these relationships. This study utilized data from a randomized controlled trial comparing NRT to standard care counseling for low-income smokers who completed daily surveys on a smartphone app assessing daily NRT use and other variables (i.e., mood, motivation, self-efficacy). The current study will examine the relationships between three types of daily NRT adherence (i.e., dose amount of short-acting NRT use, nicotine patch wear time [16 hours or more], and combination NRT (cNRT) use of nicotine patch [16 hours or more] and short-acting NRT [8 doses or more]) and same-day negative mood, motivation, and self-efficacy, as well as whether these relationships vary by gender. Three research questions were examined:

R1: Is same-day negative mood related to lower NRT adherence and is this relationship present only in women?

R2: Is same-day motivation related to greater NRT adherence and is this relationship present only in women?

R3: Is same-day self-efficacy related to greater NRT adherence and is this relationship present only in women?