Predicting complete loss to follow-up after a health-education program: number of absences and face-to-face contact with a researcher

Table 2 Analyses of predictors of complete loss to follow-up.

Predictor variable		Lost to follow-up n = 50	Not lost to follow-up n = 359	Odds ratio (95% confidence interval)	Area under ROC curve, or sensitivity and specificity
Hypothesized predictors
Number of absences^a	Median (25%, 75%)	2.0 (0, 5)	0 (0, 1)	1.78 (1.49-2.12)	0.723
	95% CI	1 to 4	0 to 1
Contact^b	Yes	18	188	0.51 (0.28-0.95)	0.64, 0.52
	No	32	171
Other analyses ^c
Age^d	Mean ± SD	42.5 ± 14.1	48.1 ± 14.0	0.97 (0.95-0.99)	0.623
	95% CI	38.6 to 46.4	46.6 to 49.5
Sex	Female	40	285	1.04 (0.50-2.17)	0.20, 0.79
	Male	10	74
Schooling^e	High	23	185	0.80 (0.44-1.44)	0.54, 0.52
	Low	27	173
Marital status^f	Together	21	194	0.61 (0.34-1.11)	0.58, 0.54
	Not together	29	164
Self-efficacy^g	Mean ± SD	32.2 ± 12.5	32.2 ± 12.2	1.00 (0.98-1.02)	0.502
	95% CI	28.7 to 35.7	31.0 to 33.5
> 3 diagnoses	With	1	24	0.29 (0.04-2.15)	0.98, 0.07
	Without	49	335
Allergic disease	With	15	90	1.28 (0.67-2.45)	0.30, 0.75
	Without	35	269
Connective tissue disease	With	3	64	0.29 (0.09-0.98)	0.94, 0.18
	Without	47	295
Diabetes	With	6	59	0.69 (0.28-1.70)	0.88, 0.17
	Without	44	300
Vascular disease	With	10	55	1.38 (0.65-2.93)	0.20, 0.85
	Without	40	304
Rheumatic disease	With	4	43	0.64 (0.22-1.86)	0.92, 0.12
	Without	46	316
Fibromyalgia syndrome	With	5	27	1.37 (0.50-3.73)	0.10, 0.92
	Without	45	332
Cardiovascular disease	With	0	24	0^h	1.00, 0.07
	Without	50	335
Cancer	With	2	21	0.67 (0.15-2.95)	0.96, 0.06
	Without	48	338
Asthma	With	3	18	1.21 (0.34-4.26)	0.06, 0.95
	Without	47	341
Depression	With	4	13	2.31 (0.72-7.40)	0.08, 0.96
	Without	46	346
Pulmonary disease	With	3	10	2.23 (0.59-8.39)	0.06, 0.97
	Without	47	349

For the number of absences, the table shows medians, 25th & 75th percentiles, and 95% confidence intervals.
For the other two continuous variables, the table shows means ± SDs, 95% confidence intervals, and areas under ROC curves.
For each categorical variable, the table shows numbers of people in each category, odds ratio and its 95% confidence interval, sensitivity, and specificity.
^a Number of absences from program sessions; minimum = 0, maximum = 6. Odds ratio from simple logistic regression.
^b No: did not have in-person contact with one of the researchers; yes: did have contact, once, at the time baseline data were collected.
^c Analyses of predictors studied previously or suggested during peer review.
^d Age in years. Odds ratio from simple logistic regression.
^e Low: high school or less; high: college or more.
^f Together: living together; not: all others
^g Score on a 0-to-60 scale measuring self-efficacy to manage symptoms; odds ratio from simple logistic regression.
^h Because no people with cardiovascular disease were completely lost to follow-up, there was complete separation in the "complete loss to follow-up" category. For a conservatively-biased estimate, changing the 0 to 1 and the 50 to 49 would yield an odds ratio of 0.29 (0.04-2.15).

ISSN: 1471-2288