Prevalence of Sialorrhea in Patients Treated With Clozapine

BACKGROUND:

Clozapine is an atypical antipsychotic drug considered the "gold standard" in the treatment of resistant psychosis and also in patients who have had adverse effects with others drugs previously indicated as first line. It has been described that almost two thirds of patients who do not respond to first and second generation antipsychotics respond to clozapine treatment. Despite its effectiveness in positive, negative symptoms and the risk of suicide, clozapine presents a risk of adverse effects ranging from potentially dangerous ones. such as agranulocytosis or myocarditis, to others that are considered mild but that they can compromise the quality of life of patients and non-compliance. One of these mild, but extremely annoying, side effects is sialorrhea. The prevalence of sialorrhea secondary to clozapine reported by different studies range from 30% to 80% and it seems to be a dose-dependent relationship. This great variability observed in the studies probably has to do with the tendency that clinicians have to underestimate this side effect. In addition, the presence of sialorrhea can impact negatively in the subject causing a decrease in self-esteem and feeling of security, greater social isolation and an increase in stigma.

JUSTIFICATION OF THE STUDY:

Due to the consequences that sialorrhea has on the quality of life perceived by people in Clozapine treatment and the relationship with possible therapeutic abandonment, in addition to the low systematic evaluation of this side effect, it is considered relevant to establish a systematic evaluation of clozapine induced sialorrhea in the different mental health devices of our center.

OBJECTIVES:

To measure the prevalence of sialorrhea in patients treated with clozapine and its impact on subjective perception of quality of life. The possible relationship between the Clozapine dose and sialorrhea severity, as well as severity prediction will be evaluated based on the clinical and sociodemographic variables collected.

HYPOTHESIS:

1. The prevalence of sialorrhea in people treated with clozapine is at least 30% of patients receiving this antipsychotic treatment.
2. The presence of sialorrhea is directly related to a worse perception of the perceived quality of life in patients treated with clozapine.
3. The presence of sialorrhea is directly related to the prescribed dose of clozapine, presenting a dose-dependence relationship.
4. There is an association between the total daily dose of clozapine and the severity of sialorrhea in patients treated with clozapine.

MATERIAL AND METHODS:

Study design:

A quasi-experimental study will be carried out to measure the prevalence of sialorrhea in patients treated with clozapine in different Units of the INAD.

To estimate the sample size, people with the diagnosis of schizophrenia or schizoaffective disorder will be collected in the Units above mentioned in 2018, it was a sample size of 250.

Based on that the incidence of refractory schizophrenia is around 30% to 50% of cases, the number of patients potentially candidates to be treated with clozapine would be 125.

The final sample size has been calculated with the following tool available on the web http://.fisterra.com/mbe/investia/9samples/9samples.asp, with a 95% confidence interval and an accuracy of 3%, expecting sialorrhea in 30% of the cases and including a proportion of losses around 15%. The final sample will be 129 patients.

Methodology:

Nursing team will be responsible to inform the patients about the study, to enroll them and to obtain informed consent. Also they will administer 3 clinical scales previously used in hypersalivation studies (Maher et al. 2016; Wai Hong Man, Jantine Colen-de Koning, Peter Schulte and Ingrid van Haelst 2017) through the direct observation of the sialorrhea presented by the patient with stable treatment with clozapine. The scales will be administered only once and there won't be any longitudinal follow-up.

The scales are:

1. The Nocturnal Hypersalivation Rating Scale (NHRS): A validated scale of 5 items used to assess the severity of nocturnal salivation. Scores range from the non-presence of nocturnal salivation to wake up a minimum of 3 times during the night due to hypersalivation (Spivak et al. 1997).
2. Drooling Severity and Frequency Scale (DSFS): A validated scale to evaluate the severity of daytime sialorrhea (Rashnoo and Daniel 2015). Scores range from no presence of sialorrhea to a profuse sialorrhea where saliva wets the body or even objects and furniture (saliva falls on the table when the person is sitting) based on a 5-point scale. Both severity and frequency scores are added to give a final score of the daytime sialorrhea.
3. Impact on the quality of life scale: It is a 5-point scale that range from no impact on quality of life to a major problem.

In addition, sociodemographic variables such as age, date of birth, race, date of diagnosis, as well as variables clinics such as diagnosis, years of disease evolution, total daily dose of Clozapine treatment and other prescribed treatments.

All this information will be included in an anonymous database (subjects will be identified by a study code and the database will not include personal data).

Statistic analysis:

The data analysis will be carried out using the Statistical Package for the Social Sciences (SPSS statistical program), version 25.0. The distribution of the sociodemographic and clinical characteristics of the sample will be analyzed using descriptive statistics. Likewise, to describe the possible linear associations between quantitative variables related to clozapine and sialorrhea will use the coefficient of correlation. Finally, an exploratory regression analysis will be done to predict the severity of the sialorrhea based on clinical and sociodemographic variables. The limitations of the study will be the foreseeable studies of quasi-experimental studies: that do not allow establishing cause-effect relationships between variables or calculate incidence.