Effectiveness of a PLISSIT model intervention in patients with type 2 diabetes mellitus in primary care: design of a cluster-randomised controlled trial

Design and setting

This study is a cluster RCT, registered at the Dutch Trial Registry (NTR4807). The
study protocol was peer-reviewed by the Dutch Diabetes Research Foundation. The study
was approved by the Medical Ethics Committee of the VU University Medical Centre in
Amsterdam, The Netherlands.

The study will be conducted in primary care practices in the western part of the Netherlands:
the West-Friesland region, the Zaanstreek-Waterland region, and Amsterdam area. Both
urban and rurally located general practices will be included. Randomisation takes
place at the level of general practice. Eligible patients will either be included
in the intervention or control group: structured sexual counselling based on the PLISSIT
model versus unstructured sexual counselling (usual care).

Study population

The inclusion criteria concern men and women aged 40–75 years with T2DM, who indicate
to be unsatisfied about their sexual function and want to talk about their sexual
problem with their GP. In addition, participants have to be able to read, write, and
understand the Dutch language, which is necessary for filling out the questionnaires
and talking to their GP. Participation in other scientific studies that aim to improve
one or more of our outcome measures will result in study exclusion.

Recruitment

All potential participants will be notified about the start of the study through posters
in the GP’s waiting room. In addition, the practice nurse can give written information
about the study. Recruitment of eligible patients is performed by the GP’s practice
nurse. Given the frequent three-monthly meetings this will efficiently fit in routine
care. Patients will be unaware of the practice’s randomisation status.

The practice nurse will ask all patients with T2DM aged 40–75 years to fill out a
short screener questionnaire for scientific research. We use the Brief Sexual Symptom
Checklist for men (BSSC-M) and women (BSSC-W) to screen for sexual dysfunction and
dissatisfaction about sexual function in primary care (Fig. 1 and 2) 43]. We have slightly modified this questionnaire by changing question 5 from ‘would
you like to talk about it with your doctor’ to ‘would you like to talk about it with
your GP’. In addition, we added a sixth question for patients who might want to talk
about their problem with another GP than their own.

Fig. 1. The modified Brief Sexual Symptom Checklist for Men (BSSC-M)

Fig. 2. The modified Brief Sexual Symptom Checklist for Women (BSSC-W)

Based on the results of the screener, patients are eligible for study participation
if they report 1) to be sexually dissatisfied, and 2) that they would like to talk
about their sexual problem with the GP. The practice nurse will explain that a scientific
study program is tested in this practice, and that the particular patient is eligible
for participation. Participation implies that the patient will need to fill out three
questionnaires in the coming 12 months.

After handing in the baseline questionnaire, the patient receives an information leaflet
from the practice nurse on Diabetes and Sexuality. In the intervention group, the
practice nurse will subsequently make an appointment with the GP for each patient
to talk about sexual problems. Practice nurses in the control group do not automatically
make an appointment with the GP for every patient. Instead, the practice nurse will
ask whether the information leaflet was of sufficient help or whether the patient
would like to have an appointment with his/her GP nevertheless.

The practice nurse will fill notify the researchers if a patient consented to participate.
A non-response form is filled out for those patients who do not agree to fill out
the screener and/or do not want to participate in our study. The form includes the
patient’s gender, year of birth, and ability to speak/read Dutch.

Training of practice nurses

All practice nurses will receive one training session. Intervention and control practices
will be trained in separate sessions to prevent contamination. The first part of the
training focuses on the effects of sexual dysfunction in T2DM and about discussing
sexual issues in clinical practice. Suggestions for an appropriate attitude and skills
needed for introducing sexual issues are explained. This part of the training is deemed
necessary for optimal recruitment of patients.

The second part of the training focuses on recruitment of eligible patients for study
participation, as described above. Practice nurses will be taught to explain the study
purposes, handing out the screener questionnaire, processing the results from the
screener, and recruiting eligible patients for study participation.

The practice nurses will be instructed to include at least three eligible men and
three eligible women per practice. The steps of the recruitment process will be practiced
and references to relevant literature for further reading will be provided. The training
will be given by two skilled researchers. A questionnaire to measure the practice
nurse’s knowledge and competence with discussing sexual problems in patients with
T2DM will be administered before and 3–4 weeks after the training.

Intervention development

During the first step of the model, Permission, the care provider invites the patient
to talk about sexual health and sexuality. One way to do so is by asking certain ‘cue
questions’, such as ‘I ask all my diabetes patients about their sexuality, is it okay
if I ask these questions to you now?’ or ‘People with diabetes often have questions
about how diabetes may affect their sex life. Is there anything you would like to
ask me?’. Permission here refers to explicit permission-giving by the patient to talk
about this (yes/no) with the care provider. On the other hand, Permission also refers
to the normalisation of sexual problems by the care provider (implicit permission-giving)
44]. The second step, Limited Information, concerns providing general information, for
example regarding the effect of diabetes on sexual function. The first two steps of
the PLISSIT model focus on the invitation to the patient to talk about sexuality and
on the normalisation of the sexual problem 45].

Compared to the previous steps, the care provider needs additional skill and knowledge
to carry out the third step of the model, Specific Suggestions. In order to provide
relevant suggestions, the care provider needs to understand the patient’s particular
complaint, which may include taking a sexual history 45]. Examples of specific suggestions may include the use of lubricants, lifestyle changes,
or medication adjustment. These suggestions are aimed to directly help the patient
within a relatively short period of time 45].

Since most GPs will not be skilled enough to perform the fourth step of the model,
Intensive Therapy, this step will almost always include referring the patient to specialised
care. Step four may be applied to complex sexual problems or problems that were not
efficiently helped in the previous steps. For example, referral to a sexologist or
psychologist may be necessary in case of relationship problems or sexual abuse 44]. The PLISSIT model thus provides a framework for when referral is appropriate, but
most importantly, the model aids the care provider with the discrimination between
problems for which brief therapy will suffice (step 1–3) and problems needing intensive
therapy (step 4) 45].

Training of GPs in the intervention group

GPs in the intervention group will receive one training session regarding the application
of the PLISSIT model. General information about sexual (dys)function and T2DM will
be provided. Role-play will be used to help the GPs become aware of their attitudes
towards sexual health and sexuality. After the exercise, attitude and skills needed
for discussing sexual problems will be discussed. The training continues with a thorough
explanation of the steps and the application of the PLISSIT model, including relevant
examples for each stage of the model, which may include, but are not limited to:

1) Permission: examples of certain ‘cue questions’ will be given. For instance, ‘I
ask all my diabetes patients about their sexual health, it is not an easy subject
to talk about, but we know that many diabetes patients suffer from sexual problems.
Is it okay to talk with you about this now?’.

2) Limited Information: explanation of normal sexual functioning; explanation of the
association between T2DM and sexual problems; and providing adequate additional information
choosing from a variety of available information leaflets regarding sexuality and
chronic illness.

3) Specific Suggestions: a training in taking a short sexual history with respect
to the age, gender, ethnicity, and sexual orientation of the patient. In addition,
multiple examples of ‘specific suggestions’ will be given, such as prescribing lubricants
or phosphodiesterase-5 inhibitors, or providing (further) psycho-education on facilitating
and impeding factors of sex.

4) Intensive Therapy: explanation of when to refer to which specialist, e.g. sexologist,
psychologist, or gynaecologist. An overview of the local referral possibilities will
be handed out during the training.

It will be emphasised that GPs should apply the model geared to an individual’s problems
and needs, and that, consequently, not all steps are necessary for every patient.
The model should not be interpreted as a linear structure, but as a dynamic process
of consultation, including, when necessary, returning to previous steps or skipping
one 44]. During the training, the application of the PLISSIT model will be practiced based
on a theoretical case. Afterwards, references to relevant literature for further reading
will be provided.

An experienced GP who also works as a certified sexologist will train the GPs in the
intervention group. A questionnaire to measure the GP’s knowledge and competence with
discussing sexual problems in patients with T2DM will be administered before and 3–4
weeks after the training.

Intervention

In the intervention group, a consultation with the GP is scheduled two weeks after
the meeting with the practice nurse. The GP will discuss the patient’s sexual problems
according to the steps of the PLISSIT model, as described previously. Only after permission
is given (step 1), the intervention will continue. In case the patient doesn’t give
permission, the GP will emphasise that the patient may always raise this issue at
a later moment 44]. The following steps of the model will be addressed based on the patient’s needs,
allowing the GP to return to previous steps or to skip steps not deemed necessary.
Since the majority of the patients will be helped by discussing the first three steps
of the PLISSIT model, most of the counselling will take place in one or two consultation(s).
Multiple consultations are expected to be necessary for (more) complex sexual issues
in step 3 and 4.

If the GP suspects the patient to express depressive symptoms during the PLISSIT consultation,
the GP will treat first what he/she deems necessary. The patient will receive care
conform the NHG guideline for depressive symptoms 46]. When depressive symptoms are treated first, the GP will make a PLISSIT appointment
after a clinically relevant interval.

Control group

GPs in the control group provide care as usual 21]. At present, apart from the NHG guideline about ED 47], no NHG guideline regarding male or female sexual dysfunction exists. The GP will
provide usual care conform the NHG guideline on depressive symptoms when deemed necessary
46], as previously described in the intervention strategy paragraph.

In order to establish equal referral options for both study arms, GPs in control practices
will receive the same overview of specialists to whom they may refer their patients
for further treatment. By providing both groups with this map we can correct for the
effect a referral may have on our outcomes.

Data collection and outcome measures

The following outcome measures are included in the questionnaires.

Primary outcome measures

Sexual function will be assessed with the 19-item Female Sexual Function Index (FSFI)
for women 48], and the 15-item International Index of Erectile Function (IIEF) for men 49]. Both questionnaires are widely used and have been well-validated 50]–52]. Satisfaction with sexual function will be measured on a 10-point Visual Analogue
Scale (VAS) scale: ‘how satisfied are you with your sexual functioning on a scale
from 0 to 10?’, where 0 indicates being very unsatisfied and 10 indicates being very
satisfied. Quality of life will be assessed with the brief, reliable, and valid Short
Form-12 item survey (SF-12) 53]–55].

Secondary outcome measures

The 9-item Patient Health Questionnaire (PHQ-9) will be used to measure depressive
symptoms 56]. The PHQ-9 has been validated in several (clinical) populations, and has shown to
have good reliability, and high sensitivity and specificity for depression in patients
with T2DM 57], 58]. The revised version of the Female Sexual Distress Scale (FSDS) 59], the FSDS-Revised (FSDS-R) 60], will be used to examine sexual distress. Consistent with the FSDS, the FSDS-R showed
good psychometric properties for assessing sexuality-related personal distress in
women 52], 59], 60]. We will use the FSDS-R to assess sexual distress in women. In addition, for exploratory
purposes, we will use the FSDS-R to assess sexual distress in men. The World Health
Organisation-Five Well-Being Index (WHO-5) will be used to measure emotional well-being,
which has shown good psychometric properties as a screener for depression in patients
with type 1 and 2 diabetes 61]–63]. Finally, patients’ treatment satisfaction will be examined in qualitative interviews.

Process analysis

To assess whether the study protocol was followed as intended, we ask all patients
at three (T1) and 12 (T2) months follow-up whether they received the information leaflet
on diabetes and sexuality from the Dutch Diabetes Association and whether they had
a conversation with the GP about sexual problems. In addition, we will ask about the
number of return visits regarding sexual problems, and whether the patient was referred
to another health care provider for this sexual problem.

A second part of the process analysis concerns qualitative research. All patients
will be asked whether they may be approached for a telephone interview during the
study. We will perform a purposeful sampling approach, taking the patient’s age, gender,
and sexual functioning into account. An estimate of 15–20 interviews is necessary
1) to assess whether the intervention or the control procedures were performed according
to the study protocol; and 2) to examine treatment satisfaction. The interviewer will
be unaware of the patients randomisation status and sexual functioning.

Sample size

We decided to settle for a power to detect an improvement of 25 % in sexual functioning,
10 % in the control group and 35 % in the intervention group. We calculated that 65
participants per group would be needed, assuming a two-sided test at an alpha of 0.05
and a power of (1???beta) 0.90. Due to cluster randomisation at GP level, the sample
size needed to be inflated based on the formula of the Design Effect: 1 + (n-1)?ICC
with n as the mean cluster size and ICC as the Intracluster Correlation Coefficient
64]. We estimate to recruit six eligible patients per practice (n=6). An ICC of 0.05
was chosen to account for the clustering of patients within practices 64], 65]. The Design Effect was calculated as 1.25. In addition, we accounted for a 20 % dropout.
A total of 195 patients are needed. We will therefore aim to recruit 200 patients
from 34 general practices.

Randomisation and blinding

An independent statistician will randomly allocate the participating general practices
to either one of the study arms by means of block randomisation. Practices will be
matched based on location and number of patients with T2DM per practice. In addition,
when necessary, we will account for practice nurses who work in multiple general practices
by matching those practices in one block to ensure that practice nurses that work
in different participating practices have a similar allocation in each practice. Patients
will be unaware of the randomisation status, as is the analyst during the data handling
and data analysis; GPs and practice nurses cannot be blinded.

Analyses

Since we have chosen a cluster-randomised design with repeated measurements, observations
and patients within a certain cluster are more alike and thus correlate to each other.
We will therefore use linear and logistic multilevel regression analyses to study
the effects of our trial. Data will be analysed as intention-to-treat and differences
in outcomes measures between the intervention and control group will be calculated
with 95 % confidence intervals. Given that not every patient in the control group
will have had an appointment with their GP, a sensitivity analysis will be conducted
to compare patients who had an appointment with their GP in the intervention versus
control group.