Effects of a brief, pedometer-based behavioral intervention for individuals with COPD during inpatient pulmonary rehabilitation on 6-week and 6-month objectively measured physical activity: study protocol for a randomized controlled trial

The study center in Erlangen will contact subjects via letter 6 weeks (t3) and 6 months (t4) after discharge from the inpatient PR program. Provided that participant’s current health status along with any other considerations (e.g., holidays) do not preclude wearing the PA monitor, the device and follow-up questionnaires will be sent to the subjects for t3-PA and t4-PA measurement. If the PA monitor and the questionnaire has not been returned within 2 weeks, postal reminders will be sent.

This study recruits patients with COPD assigned to PR. In some cases, after the physical examination in the rehabilitation clinic, initial diagnoses are proven incorrect after already having completed the t0 measurement at home. These cases are not classified as dropouts but as being falsely included initially. Dropouts for study phase I are defined as patients who provided an informed consent for phase I but refused to complete the baseline evaluation (t0). Dropouts for study phase II are defined as patients who provided an informed consent for phase II but refused to complete one or more of the following measurements (t1–t4). Additionally, dropouts are classified as patients who withdraw from the study during phase I or phase II and prohibit the use of existing data. Subjects who did not complete treatment, or who did not complete assessment at the end of the inpatient PR but do not explicitly refuse or withdraw from the study, will be followed up. Figure 1 illustrates the flow chart of study subjects.

The registration of all eligible patients and the reporting of the number and sex of eligible patients who do not participate in the study will take place for both study phase I and study phase II.

The control group (CG) will receive standard PR. Standard PR is an intensive and comprehensive inpatient PR in a specialized German rehabilitation clinic. This PR is described in further detail below. In addition, the CG receives a “behavior placebo” intervention during their PR. This intervention contains playful PA and revisions of information on PA (knowledge on exercise recommendations, knowledge on possibilities of self-regulation of endurance training exercise intensity) obtained earlier during patient education of the standard PR. Similar to the IG subjects, the CG receive a booklet that looks identical to the PA diary used in the IG. This booklet contains a repetition of PA-related information from the standard PR curriculum.

PR in the Bad Reichenhall Clinic. In Germany, PR is usually carried out as inpatient rehabilitation and generally lasts 3 weeks, an extension of 1 to 2 weeks is possible if necessary. PR is a comprehensive, multidisciplinary intervention based on an initial assessment followed by a combination of patient-tailored therapies [1, 19]. In the Bad Reichenhall Clinic PR lasts an average of 25 days, is tailored to the patients’ individual needs and includes the following obligatory main components: checking and, if required, adjusting the current COPD medication according to COPD guidelines; physical exercise (4–5 units/week of endurance exercise (45 min) and 3 units/week of strength exercise (45 min) per week, and 7 units/week whole-body vibration muscle training); structured COPD patient education (6 h of patient education COPD + 1 h inhaler device training), respiratory physiotherapy in groups (pursed lips breathing and other breathing and coughing techniques (2 units/week of 45 min)). Optional components include a comprehensive smoking-cessation program (at least 8 units), mucolytic physiotherapy, inspiratory muscle training (IMT), neuromuscular electrostimulation (NMES), saline inhalation therapy, psychological interventions and social counseling (individual and groups), nutritional counseling, patient education concerning long-term oxygen therapy, and occupational therapy including counseling on assistive devices. PR in Bad Reichenhall Clinic is implemented by an interdisciplinary rehabilitation team including experienced pneumologists who bear overall responsibility and coordinate the program along with further health professionals including physiotherapists, exercise therapists, occupational therapists, psychologists, social workers, nurses and nutritionists.

For all patients – IC and CG – receiving PR in the Bad Reichenhall Clinic, treatment includes several intervention components addressing the promotion of PA. Additional file 1 lists the behavior-change techniques (BCT) included in standard care in the Bad Reichenhall Clinic according to the taxonomy of BCT from Michie et al. [11].

Subjects in the intervention arm will receive the same standard inpatient PR program as the control arm. Instead of the placebo intervention of the CG the IG will additionally receive a pedometer-based PA BCI.

The central components of the BCI include the following behavior-change techniques (BCT):

The BCI integrates the most frequently applied BCT for PA promotion in patients with COPD [20]. Additional file 2 explicates the sequence of the two BCI lessons and defines the used BCT with regard to the BCT taxonomy [11].

The BCI will consist of two 45-min sessions. The first lesson is placed in the end of the second week of PR and the second lesson will take place in the middle of the third week of PR. During lesson 1 of the BCI, subjects receive a pedometer and booklet containing a PA diary and PA-related information (recommendations for exercise and PA for patients with COPD). Subjects keep the pedometer and the booklet after their PR discharge. The intervention replaces standard exercise therapy and for this reason the total amount of therapy is identical. The BCI is delivered in open groups (varying composition of subjects possible) with six to 12 patients. An exercise therapist from the clinic will hold both lessons. As BCT included in the sessions relate to PA, the lessons take place in a gymnasium.

With regard to session length, placement (2 × 45 min in weeks 2 and 3 of the PR) and group composition, the CG lessons are identical to the IG.

The primary outcome is objectively measured PA at 6 weeks (t3) and 6 months (t4) after PR. Baseline measurement of PA is conducted 2 weeks before the inpatient PR begins (T0). PA is measured on seven consecutive days with a three-axial accelerometer PA monitor (Actigraph wGT3X-BT). This activity monitor is the one of the most accurate devices for COPD patients and is explicitly recommended as a valid tool to measure PA in this clinical population [21‐23].

Secondary outcome measures will assess central psychological and physical functional determinants of long-term health-promoting PA applicable to patients following PR. As defined by the PARC model [24] the following characteristics will be collected: physical motor functions and consequences of health problems in functioning (physical function and disease-related impairments in activities and participation), motivation and volition, sports-related goals and motives, stage of behavior change, as well as characteristics of health and wellbeing. Data will be entered and stored at the Erlangen Study Center. Outcomes of the study and time frames for their collection are shown in Fig. 2.

Regarding the primary objective, a baseline-controlled comparison (covariance) of the post values between the initial assigned control and the intervention treatment group (intention-to-treat analysis) at the time points t3 and t4 will be provided for statistical analysis.

For the secondary objective a cluster-based analysis method will be used for longitudinal records (e.g., linking of clusters after removal of a residue (LICUR); [25]). In this case the analysis creates separate clusters for each measurement using the comprehensive assessment battery for t1 and t2 and especially using the accelerometer PA data for t0, t3 and t4. The second step of the cluster-based analysis links separately created clusters in a longitudinal way.

A strategy for dealing with missing data will be developed in cooperation with a biostatistician. If adequate and realistic, missing data will be substituted by multiple imputation.

The processing of PA monitoring data as the primary outcome will be conducted as follows: the PA monitor will be worn for seven consecutive days with a minimum of four valid days inclusive of a weekend day [26‐28]. A day is considered valid if subjects wear the device for ten or more waking hours [26‐28], where non-wear time is set at 60 min of zero counts of which up to 2 min may be within the 0–100 count range [28, 29]. Current research points towards avoiding the use of direct monitor outputs such as energy expenditure estimations due to issues with reliability [21, 30]. Consensus points towards the use of both sedentary and moderate to vigorous physical activity (MVPA) cutoff points where sedentary activity is seen as 0 to > 100 counts per min [27, 29, 31, 32] and MVPA as > 1952 counts per min [29]. While the use of the LFE filter to calculate steps is not recommended, it may be applicable during data analysis of cutoff points for older adults [33, 34]. Future work on defining cutoff points in clinical populations will be considered.