Oral health-related quality of life after prosthetic rehabilitation: a longitudinal study with the OHIP questionnaire

Subjects

The study was conducted among Hungarian adults undergoing oral rehabilitation. Data
were collected from September 2010 to December 2011 in the Faculty of Dentistry of
the University of Debrecen and in 13 related outpatient clinics from urban and rural
communities. Inclusion criteria were as follows: age???18 years, need for prosthetic
replacement, ability to complete the OHIP-49-H questionnaire without assistance. The
Institutional Review Board of the University of Debrecen approved the project. All
participants signed an informed consent form.

Questionnaire

The instrument of the present investigation (OHIP-49-H) was the Hungarian adaptation
of the original 49-items version of the self-administered OHIP-49 questionnaire developed
by Slade and Spencer 2]. Items were grouped into seven subdomains and respondents were required to answer
the questions according to the frequency of the problems using a 5-point Likert scale
(0, never; 1, hardly ever; 2, occasionally; 3, fairly often; and 4, very often) according
to the proposal by Slade and Spencer based on the assumptions made by Locker et al.
10]–12]. OHRQoL of the respondents was characterized by the sum of the subdomain scores,
the total OHIP-49-H score according to the recommendation of John et al. 13]. All subdomain effects were statistically significant and not too different in magnitude
and correlated highly and significantly with the total score (data not shown). A lower
total score represented less, a higher score more impaired OHRQoL.

An additional non-comparative question concerning patients’ oral health condition
was added to OHIP-49-H in order to confirm the construct validity of the method:

1. How do you rate your own oral health at the moment?

The oral health condition was registered by a five-grade scale (0, excellent; 1, very
good; 2, good; 3, fair; and 4, poor) using lower scores for better status. Evaluating
the first 203 questionnaires, associations between the above non-comparative question
and total OHIP-49-H scores in different phases of care were evaluated using Spearman’s
rank correlation.

Data collection

The OHIP-49-H questionnaires were completed by 389 consecutive prosthetic patients
(214 patients from the university outpatient clinic and 175 patients from community
outpatient clinics in urban and in rural environments) before dental treatment without
assistance on first admission (T0-phase), and were examined and treated by the working
group of authors. The corresponding patients were selected sequentially with their
admission without any special selection process. The same questionnaire was completed
again by 235 patients (176 patients from the university outpatient clinic and 59 patients
from community outpatient clinics in urban and in rural environments) 1 month (T1-phase)
and 92 patients (60 patients from the university outpatient clinic and 32 patients
from community outpatient clinics in urban and in rural environments) 6–12 months
after treatment (T2-phase), respectively 9].

Oral examination and treatment: Cariological and periodontal condition of the participants
were documented. DMF-T index was calculated as published previously by Baume 14]. Community Periodontal Index (CPI) was calculated to describe the periodontal status
15].

At baseline (T0-phase) patients were categorized into three groups according to the
types of dentures: those having fixed dentures or wore natural dentition (FPD); those
with partial removable dentures (RPD); and those with complete dentures (CD). In cases,
when someone wore different dentures in the upper and lower jaws or wore a combined
denture in the same jaw the most debilitating type of denture had been considered
9]. According to the types of prosthetic interventions nine subgroups were distinguished
(Table 1). Ten patients who were complete denture wearers at baseline and were rehabilitated
with fixed or partial removable dentures, received implants.

Table 1. Application of different types of prosthetic rehabilitation

Data analysis

The median interquartile range (IQR) values of the total OHIP-49-H score were calculated
for T0-, T1- and T2-phases. We established the correlation between total OHIP-49-H
scores of the follow-ups and the minimally important difference (MID), that defines
the smallest change in a treatment outcome that a patient would identify as important
16]. Evaluating the first 203 questionnaires, reliability of the OHIP-49-H was checked
by Cronbach’s statistics 17]. Spearman correlation test was computed in order to assess the association between
non-comparative question concerning patients’ oral health condition and OHIP-49-H
scores. Treatment-associated changes in OHRQoL were evaluated by Mann–Whitney U test.
Relationships between clinical parameters and changes of OHIP-49-H scores were investigated
by stepwise multivariate logistic regression analysis comparing the T0- and T1-phases
of the study, after dichotomizing the outcomes according to the observed median values.
We used stepwise multivariate logistic regression analysis when we had one nominal
variable and two or more measurement variables, and we wanted to know how the measurement
variables affected the nominal variable and to understand the functional relationship
between the independent variables and the dependent variable, to try to understand
the likely cause of the change in the dependent variable. The level of significance
was p??0.05.