ObjectiveQuality of life (QoL) is one major outcome parameter in the care for people with dementia (PwD); however, their assessment is lacking a gold standard. The purpose of this study was to evaluate potential factors associated with nurse-rated quality of life of PwD in nursing homes in Berlin, Germany.MethodAn explorative cross-sectional study was performed in five nursing homes to evaluate QoL. Nurses rated the QoL for all residents with dementia by completing two different standardised assessments (ADRQL, QUALIDEM). Potential associated factors were evaluated concerning resident and nurse related factors. A fixed-effects models of analysis of co-variance (ANCOVA) was used to analyse effects of assumed associated factors of the major outcome parameters ADRQL and QUALIDEM. Associated factors were severity of dementia (GDS), challenging behaviour (CMAI), and other characteristics. Regarding the nurses, burnout (MBI), satisfaction with life (SWLS), attitude (ADQ) and empathy toward residents (JSPE), as well as circumstances of the ratings and days worked in advance of the ratings were assessed.ResultsIn total, 133 PwD and 88 nurses were included. Overall, the ratings show moderate to high QoL in every subscale independent of the instrument used. Assumed confounders relevantly influenced 14 out of 17 ratings. Predominantly, residents’ challenging behaviour, nurses’ burnout and satisfaction with life as well as the circumstances of the ratings are significant and clinically relevant associated factors.ConclusionAssessing QoL of PwD is acknowledged as a central component of health care and health care research. In later stages of dementia, proxy-reported information obtained from quality of life questionnaires is and will continue to be essential in this research. However, methodological issues that underline this research - matters of measurement and instrument validity - must receive more attention. Associated factors in proxy-ratings have to be routinely assessed in order to get more valid and comparable estimates.