The effects of illness on QoL can be related to the impairment, disability and handicap [15
]. In this study, we evaluated of generic and oral QoL in overall OMDs during routine clinical activities, and compared the data of OHIP-14 and SF-36 between OMD and HS. The results yield additional information that may be relevant and useful for the clinical management of patients with OMD.
Our study is institutional based research. All patients studied were recruited at the Department of Oral Mucosal Diseases, Shanghai Ninth People's Hospital. Part of the HS were recruited from a local community in Shanghai, which was a relatively stable community. The others were recruited from the family members of patients with OMD studied. Some of the family members of patients refused to participate the study. Therefore the size of HS was lower than that of overall OMD patients.
OMD are common, and many of them are unknown cause. Patients with OMD can be suffered from life-threatening symptom and be influenced daily life in many ways which including a psycho-social effect as well as a functional impact. Measurement of QoL may help to assess unknown cause conditions. Mumcu et al. used OHIP-14 and SF-36 to measure the oral and general health related QoL in the patients with Behçet's disease, RAS and healthy controls, and observed worse oral QoL in these patients [10
]. McGrath C et al. evaluated the sensitivity of two patient-centred outcome measures to the topical application of a corticosteroid (betamethasone) in the treatment of OLP by UK Oral Health Related Quality Of Life measure (OHQOL-UK) and OHIP-14 [7
]. Previous research results also indicated that clinical oral disease such as BMS and dry mouth could affect life quality using OHIP-14, OHIP-49 and SF-36 [5
]. Tabolli et al. used both specific and generic instruments including OHIP-14, SF-12, and 12-item General Health Questionnaire questionaires (GHQ-12) to study QoL affected by various oral mucosal conditions [16
]. They found that OMDs radically affected QoL and were accompanied by a high frequency of psychological problems. The similar result could be found in the study by Llewellyn et al [17
]. They used OHIP-14 questionaire and observed the greatest impairment to QoL was register on physical pain. The measures employed in this study were a oral health-related quality of life instrument, the OHIP-14, and a generic health-related quality of life instrument, the SF-36, which had been widely used internationally. To the best of our knowledge, it is the first time that both of OHIP-14 and SF-36 were used to evaluate QoL in overall OMDs and control HS. We showed that there was a significant lower scores in generic and oral QoL for patients with OMD than that with HS. Our study suggested that the evaluation of the effects of OMD on generic and oral QoL might be considered as a part of clinical decision processes.
Discriminant validity is the validity obtained when we measure two things that are thought to be dissimilar and our measures can discriminate between them. Allen & Locker has previously discussed the discriminant validity of OHIP [14
]. They addressed that that the OHIP could discriminate between clinically disparate groups, while the SF-36 did not [18
]. Hunt et al. suggested that the SF-36 had an advantage over other similar instruments, such as the Nottingham health profile [19
]. Allen et al. reported that generic health can affect a patient's ability to tolerate dentures [18
]. Our findings indicated that the SF-36 score could discriminate between overall OMDs and HS as well as sum OHIP-14 did. The probable reason for this was that many OMDs were unknown cause and multisystem involved. However, we noticed that when OMDs categorizing into 5 groups, the mean score of sum OHIP-14 for RAS, OLP, BMS & paraesthesia and others was significantly different from HS. On the other hand, only RAS and BMS & paraesthesia could be discriminated from HS by the mean score of SF-36. The results of the study by Lopez-Jornet P et al. showed that BMS yielded poorer quality of life scores than the control group in all the domains of the questionnaires including OHIP-49 and SF-36 [11
]. This study could also show the same result between BMS & paraesthesia and HS. It would be advisable to use these in conjunction with classical instruments for clinical diagnosis [20
], meanwhile further verification with large cohort is needed.
While this study showed an overall lower SF-36 score for OMD patients, the result for the Physical Functioning sub-scale showed OMD were actually healthier on this dimension. The probable reasons for this result were: 1, OMDs were mainly confined in the oral cavity. Therefore the influence by OMDs on Physical Functioning was limited. 2, With increased age the influence of Physical Functioning could be influenced by systemic disease. The mean age of the overall respondents was over 45. A limitation of the study was that we did not perform screening for systemic disease. Therefore, 'HS' only means participants without OMD, and does not necessarily mean those without systemic disease.
In this study, the size of overall OMD and HS was not homogeneous. We failed to collect more HS, because some OMD patients' family member rejected to be involved. We also further grouped the observed OMDs into 5 categories. However, we are aware that some grouping may be arbitrary. The group named 'others' included very different OMDs and was created because of small numbers (< 30).