Table 4

Relationship between persistency index and outcome measures (mixed effects regression analysis)

Outcome(s) with adjustment^a

Intercept

Time, years

Persistency index

Persistency index × time

Beta coefficient^b (standard error)

MMSE

3.89 (2.001)

-2.58 (0.13)^c

-1.09 (0.77)

1.02 (0.23)^c

ADAS-Cog^d

55.45 (5.65)^c

3.68 (0.66)^c

-3.75 (2.09)

2.74 (1.32)^e

BPMSE

10.46 (3.47)^e

-2.55 (0.25)^c

-1.76 (1.90)

1.00 (0.52)

PSMS

10.03 (1.85)^c

1.68 (0.12)^c

-0.09 (0.66)

-0.43 (0.21)^f

IADL

18.63 (2.54)^c

2.36 (0.17)^c

4.19 (0.91)^c

-1.42 (0.29)^c

CDR-SB

11.43 (1.43)^c

1.67 (0.09)^c

1.42 (0.54)^e

-0.61 (0.17)^g

^aAdjustment made for early exposure index, gender, education, age, pre-progression rate, and the severity of disease at baseline. ^bMean change in score associated with each variable. ^cP < 0.0001. ^dWhen the linear trend and quadratic trend change were included in the model the coefficients (standard errors) for time-squared and time-squared by persistency index interaction are 0.19 (0.14) and -0.83 (0.26)^e, respectively. ^eP < 0.01; ^fP < 0.05; ^gP < 0.001; otherwise, P = not significant, based on type 3 F test. ADAS-Cog, Alzheimer's Disease Assessment Scale-Cognitive Subscale; BPMSE, Baylor Profound Mental Status Examination; CDR-SB, Clinical Dementia Rating-Sum of Boxes; IADL, Instrumental Activities of Daily Living; MMSE, Mini-Mental State Examination; PSMS, Physical Self-Maintenance Scale.

Rountree et al. Alzheimers Res Ther 2009 1:7   doi:10.1186/alzrt7