The purpose of this study is to investigate if focused information of spirometry in the invitation to preventive health checks will increase the attendance compared with a standard invitation to preventive health checks.

Background:

Lung diseases are among the most frequent and most serious ailments in Denmark. Chronic obstructive pulmonary disease (COPD) is the fourth most frequent cause of death and represents a significant burden on the health care system, the patients and their relatives. The National Board of Health in Denmark recommends spirometry to all individuals over 35 years who present at least one respiratory symptom (dyspnea, cough, wheeze or sputum production) or risk factors (prior or current smoking or relevant occupational exposure) in order to facilitate early detection of COPD. However approximately 200,000 citizens with COPD remain undiagnosed and unknown to the health care system.

Preventive health checks including spirometry can be used to detect lung diseases earlier. In a Danish municipality, the Check your Health Preventive Programme (CHPP) was initiated, offering preventive health checks to all 30 to 49 year-old citizens. This health promotion program provides the unique opportunity to evaluate single components of preventive health check in a real-life setting. Only a few previous studies have included spirometry in a preventive health check.

Over time the attendance at preventive health checks has decreased and at present the response rate is approximately 50%. Little is known about initiatives that can influence the attendance rate according to preventive health checks.

The aim of the study is to examine whether focused information on spirometry in the invitation material will influence the attendance in preventive health checks. The investigators hypothesize that spirometry as part of the preventive health check will increase the attendance in CHPP from 53% to 58% and the increase will be among prior and current smokers.

Materiel/Methods:

Check your health preventive program (CHPP):

The present study is embedded in the fourth year of the above mentioned CHPP. In CHPP, all citizens living in the municipality of Randers aged 30-49 years per 1st of January 2012 were identified in the Danish Civil Registration System. CHPP is a house-hold cluster randomized controlled trial offering a preventive health check to all 30 to 49 year old citizens in a Danish municipality during the years 2012 to 2017 (n= 26,216). The citizens were randomized by household into 5 groups of equal size, each corresponding to a specific year where they would be invited to a health check. Invitations with a prefixed appointment for the health check and information about the health check were dispatched continuously

Setting:

The health checks and the subsequent health behavioral courses are performed at a local health care center. The subsequent health interview takes place at the participants own general practitioner. The health checks will be conducted by health professionals who have experience with all measurement procedures as well as in risk communication to ensure standardization and quality.

The health check:

Prior to the health check the participants are asked to answer a web-based questionnaire regarding physical activity, self-rated health, mental health, smoking and alcohol. The clinical examination include following measures: biochemical (total cholesterol, lower density lipoprotein (LDL), glycated hemoglobin (HbA1c)), systolic and diastolic blood pressure, bodyweight, height, spirometry and Aastrands submaximal bike-test (cardiorespiratory fitness). At the end of the health check, the results are presented in a profile pamphlet including recommendations for follow up according to their risk-profile.

Execution of the health check is standardized by a written protocol and adherence is checked continuously.

Questionnaire:

Based on questionnaire data the following categorical variables will be described for all attendees:

• Age will be divided into four groups; 30-35, 36-40, 41-45 and 46-50
• Smoking status will be classified as smoker, ex-smoker, or never smoker and supplied with information about pack years.
• Airway symptoms (dyspnoea, wheezing or coughing) during the last four weeks will be divided into
• All of the time
• Most of the time
• Now and then
• Rarely
• Not at all

The present study:

This is a randomized controlled trial on attendance in preventive health check. From November 2015 until November 2016, 4,356 CHPP-citizens will be randomized further to either intervention or control in the present trial: The intervention group receives an invitation which highlights the value of spirometry as part of a health check. The invitation is made in collaboration with the Danish Lung Association and has been tested on a focus group before the invitations are dispatched. The control group will receive a standard invitation. Primary outcome measure is effect on attendance. Secondary outcome is the percentage of participants with abnormal spirometry assessed at the preventive health check. The characteristics of the 2 groups will be described according to sex, age, smoking history, spirometry values and lung symptoms. The intervention, the outcome and the group assignment in this trial are not revealed in the invitation for the citizens. Randomization is handled by an independent statistician.

Sample size:

The sample size is estimated to 4,356 participants in total and is calculated on the basis of the following assumptions: 1:1 randomization, two-sided significance level of 0.05, power of 0.9, intracluster correlation coefficient of 0.01 and with an average of 1.5 citizens in each household, we calculated the design effect to be 1.05. Calculations are further based on the objective of being able to detect a difference of 5% in effect size of attendance. The investigators determined this 5% difference to be clinically meaningful based on expert opinions and criteria employed in other research. The intracluster correlation coefficient was included to reflect a possible clustering effect of the general practitioners (n = 46), which is seldom greater than 0.01 in primary care settings.

Statistic analysis plan:

-The main outcomes Effect of the intervention on attendance will be estimated by differences in the proportion of citizens attending the health check in each of the groups. Crude and adjusted estimates of the difference in proportion will be based on binominal regression. Also these estimates will be compared with estimates based on propensity scores.

Furthermore, a descriptive analysis of attendees and non-attendees will be performed regarding sex, age, smoking history, self-reported lung symptoms and spirometry measurements. The analysis will follow the intention to treat principle.

For each of the endpoints, the number and percentage of individuals experiencing the endpoint will be presented, by randomisation group. Binominal regression will be used to estimate the difference in proportion between the two groups, and 95% confidence interval, comparing the intervention group with the comparison group. The baseline measure of the outcome will be included as a covariate in the model. If the distribution of the outcome is skewed, a log transformation will be used.

-Analysis of the baseline characteristics For the descriptive part of this study, bivariate and multivariate analysis will be performed. Continuous variables e.g. height and weight are presented as mean ± standard deviation, unless the variable has a highly skewed distribution, in which case, medians, 25th and 75th percentiles will be presented. For categorical variables, e.g. smoking status, civil status, and sex, the number and percentage of individuals within each category will be presented as absolute numbers and relative (%) frequencies. Anova will be used when comparing means or changes in means of numerical variables; and Chi2-test will be used when comparing proportions for categorical variables. Categorical outcomes will be analysed with logistic regression. The statistical significance level is set at p < 0.05. Statistical analysis will be performed using STATA 14.0 software.

Prevention of missing data :

The primary trial analysis will use an Intention To Treat (ITT) population, which includes all participants in the group to which they were randomised, regardless of the amount of intervention actually received. The only exclusion criterion is terminal illness as reported by the general practitioner.

To prevent attendees refusing to participate, households are invited together and two reminders are sent out. Furthermore, appointments are scheduled outside of work hours. Finally, we have the unique opportunity to use the Danish registers as a population-based health care database with information about the non-attendees, described below.

Treatment of missing data:

• Missing values due to incomplete clinical measurements or questionnaires Records with missing data due to incomplete questionnaires and incomplete spirometry measurements will be excluded. Sensitivity analysis will be performed and it will be considered if data are missing at random or not at random. Afterwards complete case analysis will be performed.

• Missing values of non-attendees As we have no clinical measurements or any answered questionnaires on the non-attendees, these data will be obtained from the Danish national registers. Sensitivity analysis will be performed and it will be considered if data are missing at random or not at random. Afterwards complete case analysis will be performed.

• Non-attendees will be described on following parameters:

  • Sociodemographic: Education level, sex, age, ethnicity and civil status from 2016 using Danish Civil Registration System(CRS)
  • Socioeconomics: income and transfer payments from 2016 using the Danish Civil Registration System(CRS) .
  • Contacts to their general practitioner from 2014-16 using reimbursement to the general practitioner from the Danish National Health Service Register.
  • Prescriptions of respiratory medicine from 2014-16 using the information about redeemed medication from the Danish National Prescription Register by using the ATC group R03 from 1995-2013. We categorized the drugs into rescue drugs against airway symptoms e.g. SABA / SAMA and chronic drugs against airway symptoms e.g. SABA/ SAMA, LABA/LAMA, leukotriene inhibitors, theophylline and inhaled corticosteroids.

Hypothesis:

The results from the present study are expected to contribute with important knowledge about the value of information on spirometry in invitations to health checks measured at different levels of attendance - as described above.

Legal and ethical aspects:

The study has been presented to The Scientific Ethics Committee and it is considered as routine data and thus ethical approval is not needed for the trial.

The study will comply with the declaration of Helsinki and according to the Danish Health Law each of the participants will provide written informed consent for data to be used for research. Approval by The Danish Data Protection Agency is obtained (2014-54-0704).

Inclusion Criteria:

• Citizens in the municipality of Randers per 01.01.2012
• Randomized for the fourth group of five groups in total to be invited for a preventive health check as part of the health promotion program, Check your health prevention program, conducted in the years 2012 to 2017.

Exclusion Criteria:

• Terminal illness as reported by the citizens general practitioner.