Bidirectional associations between alcohol consumption and health-related quality of life amongst young and middle-aged women

BACKGROUND:
Evidence from cross-sectional studies has suggested a positive association between moderate alcohol consumption and health-related quality of life but prospective data remain scarce.
OBJECTIVES:
To examine the bidirectional relationships between alcohol consumption and health-related quality of life using a longitudinal study design.
METHODS:
A total of 92 448 participants of the Nurses' Health Study II reported their alcohol consumption (in 1991, 1995, 1999 and 2003) and health-related quality of life (in 1993, 1997 and 2001). Using generalized estimating equations, we modelled the physical and mental component summary (PCS and MCS) scores as a function of alcohol consumption 2 years earlier (n = 88 363) and vice versa (n = 84 621).
RESULTS:
Greater alcohol consumption was associated with better PCS scores 2 years later in a dose-response manner up to ~1 serving daily [mean difference (β) = 0.67 ± 0.06 PCS units, for moderate versus infrequent drinkers]. After adjustment for previous PCS, a similar but attenuated pattern was observed (β = 0.33 ± 0.07). Moderate alcohol consumption was not related to MCS, whereas moderate-to-heavy alcohol consumption was associated with lower MCS scores (β = -0.34 ± 0.15). Higher PCS scores were associated with greater alcohol consumption 2 years later, also after adjustment for previous alcohol consumption (β = 0.53 ± 0.05 g day-1 ). MCS was not associated with alcohol consumption 2 years later.
CONCLUSION:
Amongst young and middle-aged women, moderate alcohol intake was associated with a small improvement in physical health-related quality of life 2 years later and vice versa. Moderate alcohol consumption was not associated with mental health-related quality of life in either direction.