Anexo 3.6 Matriz de análisis caso 6 N.P.M.P

Exploration of a combination of psychological factors—mood, personality, self- efficacy, locus of control, and health belief—will predict adherence and non- adherence to CPAP use.

The results from the present study utilising DA highlighted the predictive value of the following combined psychological factors in predicting adherence and non-adherence to CPAP use: mood; self-efficacy, locus of control, and health belief. Specifically, the results show that the mood sub-scales anger/hostility, vigour/activity, and depression/dejection; self-efficacy; internal health locus of control; and perceived susceptibility and benefits sub-scales of the health belief measure were significant predictors of CPAP adherence and non-adherence. The combination of statistically significant psychological predictors accounted for 59% of between-group variability. The remaining psychological factors and sub-scales were deemed to have poor predictive powers. These results support the findings of research conducted on other chronic diseases and illnesses in relation to treatment adherence (Sherbourne et al., 1992; Edinger et al., 1994; Norman & Bennett, 1995; Connor & Norman, 1996; DiMatteo et al., 2000; McFadyen et al., 2001; Stepnowsky et al., 2002; Stepnowsky et al., 2002; Wild et al., 2004; Aloia et al., 2005; Olsen et al., 2008). In particular, the results provide considerable evidence to suggest that psychological factors play an important predictive role in treatment adherence to CPAP use. Figure 11 displays the comparison profile between the CPAP adherent group and non-adherent group.

Figure 11. Profile of CPAP-adherent patients compared to CPAP non-adherent patients based on psychological predictors (mood, self-efficacy, health locus of control, and health belief).

Figure 12 depicts the significant group mean differences between the CPAP adherent group and CPAP non-adherent group. The group profile shows that patients classified as CPAP adherent reported less negative symptoms associated with mood (anger/hostility, vigor/activity, depression/dejection) than patients in the non-adherent group. CPAP adherent patients also reported more self-efficacy, having an internal locus of control, and understanding the perceived susceptibilities and perceived benefits of CPAP use. Whilst the latter two psychological factors displayed slight mean differences between groups these differences remain statistically significant.

4.2.2.1 Mood.

In the present study, mood was found to be the strongest predictor of adherence and non-adherence to CPAP use. In particular, anger/hostility and

0 5 10 15 20 25 30 35 Adherent Non-adherent M ea n s co re

vigour/activities were identified through DA to be the strongest psychological predictors of group membership depicting adherence and non-adherence. Despite limited predictive research surrounding the mood construct anger, results from Brostrom et al.’s research supports the predictive findings of the present study. Brostrom et al. (2007) were the first to investigate the prevalence and impact of negative affectivity (such as anger) in OSA patients in relation to CPAP adherence. In their study, patients who reported higher levels of anger displayed significantly less CPAP use. It is likely that anger observed in non-adherent patients in the present study may have contributed to low motivation or readiness to accept a likely diagnosis of OSA and subsequently commence CPAP use.

General literature surrounding adherence treatment and medication regime has also identified anger as a precipitating factor leading to poor adherence. For example, the researchers at Bandolier (2004) reported that adherence to treatment regime within the aforementioned context was generally improved by developing trust with patients so that anger did not impact on adherence. While it is noted that the POMS has been utilised as a measure of mood in relation to CPAP adherence studies conducted by Derderian et al. (1988), Kribbs et al. (1993), Yu et al. (1999), Bardwell et al. (2003), and Stepnowsky et al. (2012), the central focus of these studies was on depression and/or overall emotional distress as measured by the POMS sub-scales

depression/dejection and TMD. A breakdown of the entire POMS sub-scales from these studies for comparative reasons is therefore not possible. Nevertheless, Derderian et al. and Kribbs et al. did provide evidence to suggest that with effective CPAP use adherent patients displayed a decrease in anger. This evidence supports the findings of the present study.

Similarly, few studies have focused on the predictive powers of vigour/activity in relation to OSA and CPAP adherence. The present study has shown that high vigour/activity is predictive of non-adherence to CPAP use. Given this cohort of patients reported statistically significant higher levels of activity compared to the CPAP-adherent group, it is likely that regardless of mean AHI scores, they may not have been experiencing severe enough symptoms associated with OSA. It is possible that patients may have questioned the validity of their OSA diagnosis, given they might have been carrying out their daily activities “as usual”, without the identifying of symptoms of low energy and/or fatigue. However, those researchers identified above that have previously utilised the POMS have also reported limited results pertaining to the sub-scale vigour/activity making comparisons difficult. Derderian et al. (1988) and Kribbs et al. (1993) did however identify that patients who were adherent to CPAP use displayed an overall increase in vigour.

Depression was also identified as a predictor of non-adherence in the present study, a result that supports the general findings of the meta-analysis conducted by DiMatteo et al. (2000). DiMatteo et al. reported that depressed patients were three times less likely than non-depressed patients to adhere to medical treatment. However, research related to the association of depression and CPAP use has been limited to reporting positive changes in depressed patients as a result of adherence to CPAP use and has not been based on whether the presence of depression predicted non-adherence to CPAP use.

Kjelsberg et al., (2005) were one of the first to explore the predictive

authors found that depression was a statistically significant independent predictor of CPAP non-adherence. Thus, patients who exhibited symptoms anxiety and/or depression were non-adherent to CPAP use. Kjelsberg et al.’s study was one of the first to report a significant negative relationship between mood and CPAP adherence, as previous landmark studies had found mixed associations between CPAP use and mood (Bliwise et al., 1986; Pillar & Lavie, 1998). Kjelsberg and colleagues’ study suggested a link between patients’ psychological symptoms and lower levels of adherence to CPAP use. The authors concluded that mood is likely to play an important role in treatment adherence as it was likely to impact on an individual’s tolerance towards treatment. Kjelsberg et al. recommended that “treatment of their mental symptoms may be a possible therapeutic option in patients with OSA and symptoms of anxiety or depression that may contribute to improved compliance with CPAP therapy and break the vicious circle” (p. 343). However, it is important to distinguish whether identified mood disorders in OSA patients are a result of being sleep deprived (i.e., caused by OSA or a non-adherent CPAP use) or existed prior to developing OSA.