Background/Purpose:

The LupusQoL questionnaire is a disease-specific instrument for adults with lupus while the short form-36 (SF-36) is a generic questionnaire.

We aimed to compare the LupusQoL and the SF-36 questionnaires to determine if they are comparable measures of change in patients with SLE on standard of care therapy.

Methods:

We analyzed the results of SF-36 and LupusQoL questionnaires available from a group of lupus patients who were followed at the Lupus Clinic. Patients were studied if they had at least one follow-up visit within 6 month period while receiving standard of care therapy.

Each of the questionnaires, SF-36 and LupusQoL, includes 8 domains and its scores ranges from 0 (worst possible) to 100 (best possible) quality of life.  The SF-36 subscales can be further summarized into 2 component scores: the physical component summary (PCS) and the mental component summary (MCS).

The mean change in the domains scores for both questionnaires was determined by subtracting the scores of the follow-up visits from the score of the baseline visit.

We determined the correlation (Pearson) of the change in scores of LupusQoL and the change in scores of SF-36. The correlation of the comparable domains of LupusQoL was determined with the corresponding domains of SF-36. For each of the non-comparable domains of the LupusQoL questionnaire the correlation was determined with PCS and MCS individually.

Results:

99 patients (91% F) had baseline and at least one follow-up visit available.  44% were Caucasian, 33% Black, 10% Asian and 12% others. For the 99 patients 251 observations were identified for which both SF-36 and LupusQoL questionnaires were available. Age at lupus diagnosis and lupus duration at first visit were 27.2 ± 12.4 and 11.9 ± 7.7 years.  The mean SLEDAI-2K on all visits was 7.49 ± 5.21.

The correlation of the change in scores of the comparable LupusQoL and SF-36 domains ranged from 0.38-0.65.  The correlation between LupusQoL Pain and SF-36 Bodily Pain was 0.65, LupusQoL Physical Health and SF-36 Physical Functioning was 0.38, LupusQoL Emotional Health and SF-36 Mental Health was 0.56 and LupusQoL Fatigue and SF-36 Vitality was 0.48 (all p were significant). For the non-comparable domains the correlation of the LupusQoL domains with SF-36 MCS and PCS ranged from 0.02-0.33 (Table 1).

Conclusion:

The correlation of the change in the scores of comparable domains of Lupus QoL and SF-36 ranged from moderate to large. The correlation of the change in the scores of non-comparable domains of Lupus QoL and SF-36 was insubstantial to small. Thus these questionnaires measure different aspects of quality of life and both questionnaires might be used together.

Table 1.  Correlation of change in SF-36 and LupusQoL for comparable and non-comparable domains