We carried out a randomized, open-label, crossover trial, with two study periods (sequences AB/BA) and four assessment points (Figure 1). The trial was conducted in the same context of the MEMORA cohort which aims to study the relationship between patient characteristics and functional autonomy change over time among patients attending a MC [6,7].
Participants and setting
Eligibility criteria for participants were patients attending a memory visit for the first time at the MC, aged 50 years or older, living at home, accompanied by an informal caregiver, and who agreed to participate in the study. Exclusion criteria were patients whose caregiver did not wish to participate in the study, patients whose caregiver did not provide a phone contact, and patients for whom the health status would require institutionalization during the period of the study. The study was conducted at a MC of the Memory Research Center of Lyon (France), between November 2014 and April 2016.
IADL questionnaire and modes of administration
The questionnaire used to assess the level of functionnal independence (or dependence) was the French version of the Lawton instrumental activities of daily living including the 8 items: Ability to use the phone, to go shopping, preparing food, do its housekeeping, do its activities bleaching, to use transportation, to ensure accountability in respect of salary and handle money . The questionnaire answers have been considered as a total score ranging from 0 (dependent) to 8 (independent), as well as 2 sub-scores of 4 based on previous research . The first sub-score included the abilibies for phone, transportation, medications and finance, the second sub-score included the others 4 abilities. In addition, each item of the IADL questionnaire has been scored as binary variables (1: abillity to conduct the activity, 0: no ability).
The IADL questionnaire has been collected for the same patients using two modes of administration: by phone and in-person interview. Both interviews consisted of a collection of answers given by the caregiver to the nurses trained for this procedure. The questionnaire was identical in both modes of administration, the questions were asked in the same order and the nurses had to read the questionnaire exactly as it was written to ensure similar conditions for collection of data.
The potentially eligible patients were selected in the list of scheduled appointments in the MC. A letter to inform both patient and caregiver of the possibility to participate to the study was sent with the convocation for the clinical memory visit. The nurse contacted the patients and caregivers depending on the phone number available, presented the study, checked the eligible criteria and asked whether they agreed to participate. If they agreed to participate, they were assigned randomly in one of the branches of the study. For the patients in the 1st branch, the phone appointment was planned with the caregiver one month after the memory consultation. For the patient in the 2nd branch for whom the phone appointment was the first IADL measure, a phone appointment was planned with the caregiver one month before the memory consultation. In case the call did not succeed, it was expected that the nurse could call back the caregiver up to 4 times maximum, whatever the branch.
Patients and study characteristics
Additionaly to the IADL questionnaire collected during the MC visit, we considered the following patients’ characteristics collected using the eCRF of the MEMORA study during the MC visit. We focused on the following patients’ characteristics: education level, marital status, cognitive status, aetiology, the MMSE score ranging from 0 to 30 and evaluating the overall cognitive performance, and the relationship between the caregiver and the patient. Details of the collection of the data in the MEMORA study are available in previous open-access manuscript.
Additional information was collected at the second interview, either by in-person interview, either by phone in order to detect possible changes between the two measures: change of caregiver respondent between the 2 visits, change of nurse who administered the questionnaire, and the following events: entry in emergency department, hospitalization, occurrence of a fall, change of place of life, occurance of a death in the family. The number of calls needed to reach the participants, and the reason why the questionnaire could not be administered after randomization.
The randomization was performed using a computer generated random list (Excel). It was a centralized and restricted randomization with an allocation ratio of 2:2 in fixed block of 4 individuals. The washout period between the two modes of administration was approximatively 1 month. The random allocation branch was generated by a statistician. The nurses, who enrolled the patients, assigned each of them to one of the branches according to the random allocation and successively in the order of inclusion.
The sample size required was determinated with the STATA software (SSQDL function). To obtain a Cohen’s kappa coefficient of 0.8 between the two methods of administration of the questionnaire. By assuming a proportion of patients dependant for at least 2 items of the IADL questionnaire at 50%, with a power of 80% and a risk alpha of 0.05, the sample size required was 138 patients per branch. With an expected loss of follow-up or missing value rate of 30%, the total sampe size was estimated at 197 patients per branch.
Data collection and management
The IADL questionnaire and the additional information collected at the second interview were collected in paper form by the nurses and entered in an electronic case report form by the nurses after the interviews. The others characteristics of the patients were collected directly in the eCRF of the MEMORA study by the nurses. At the end of the study, the data of both eCRF were matched using the unique identification number allocated to each patient.
A flow-chart has been made to describe the selection of the population. Missing data were not replaced, nevertheless we considered that the data were analysed by intention-to-treat approach as the patients were kept in the branch to which they were originally assigned by randomization.
The characteristics of patients who had the first visit completed were compared between those who had the second visit and those who had not using the Pearson Chi-squared test or Fisher Exact test to compare proportions or independent Student t-test to compare means. The characteristics of the final study population were compared between the branches.
In our main analysis, the extent of agreement between the two modes of administration was measured (1) by calculating the proportion of participants who gave the same response for both modes of administration, (2) by estimating the Cohen’s kappa coefficient for the total IADL score, for the 2 sub-scores of IADL, for each item of the IADL score (coded as binary variables), and each level of independence according to the total IADL score e.g. independent of 8 abilities vs. 0, independent for > = 7 abilities vs less, and (3) by estimating the Intraclass correlation coefficient (ICC) for the total IADL score. The proportion of patients according to the different cases was compared using the McNemar Chi-squared test. The method of Bland and Altman was also used to evaluate the agreement between the two modes of administration for the total IADL score . These analyses were conducted in all the study population, and separately in both branches.
In an additional analysis, the associations between the patients included in the 95% limits of the Bland and Altman agreement vs. those outside, and the patient’s characteristics were assessed using logistic regression models. Analyses were performed using SPSS (Statistical Package for the Social Sciences) version 19.0 for Windows (SPSS Inc., Chicago, Illinois, USA).