Table 113Study quality checklist

ReferenceQuality assessment – study methodology
ProspectiveRepresentative population sample(a)Minimal attrition biasPrognostic factor measured appropriately(b)Outcomes adequately measuredConfounders accounted for(c)Appropriate statistical analysis(d)Quality
STERN1979✓✓✓✓✓~✘(e)LOW
STERN1984✓✓✓✓✓✘✘(e)VERY LOW
STERN1984A✓✓✓✓✓~✓ - for subgroup comparisons

✘ - for general population comparison		Subgroups: MODERATE

Main: LOW
STERN1988A✓✓?(f)✓(g)✓~✘(e)LOW
STERN1990✓✓?(f)✓✓~✘(e)LOW
STERN1994✓✓?(f)✓✓~✓ - for subgroup comparisons

✘ - for general population comparison		Subgroups: MODERATE

Main: LOW
STERN1997✓✓?(f)✓(g)✓~✘(e)VERY LOW
STERN1998A✓✓?(f)✓(g)✓~✓- for subgroup comparisons

✘ - for general population comparison		Subgroups: MODERATE

Main: LOW
STERN2001✓✓?(f)✓(g)✓~✓ (but too few events)VERY LOW
STERN2002✓✓?(f)✓✓~✓ - for PUVA dose comparisons (but too few events)

✓ - for main analysis		VERY LOW
MARCIL2001✓✓?(f)✓✓~✓LOW
NIJSTEN2003✓✘(h)?(f)✓✓~✓ (but too few events)LOW
NIJSTEN2003A✓✓?(f)✓✓~✓MODERATE
LIM2005✓✓?(f)✓✓~✓MODERATE
PAUL2003✓✓✘✓✓~✓ (but too few events)VERY LOW
PAPP2012A✘/✓(i)✓✘✓?✘✘(e)VERY LOW
VANLUMIG2012✓✓??✓✘✘(e)VERY LOW
HEARNE2008 (MAN2005)✓✓?(j)✓✓✘✘(e)VERY LOW

✘: No

✓: Yes

~: Partial

?: Unclear

a

The representativeness of the sample is based on baseline characteristics, although inclusion and exclusion criteria were not clearly stated. Although there are more skin types III+ than in the UK the geographical area also has a higher UV exposure than the UK and the exposed and unexposed samples were matched for geographic location so the sample is deemed appropriate

b

Limited reliance on recall

c

See Table 114 for detailed information on controlling for confounders

d

Note that the method of calculating RR for subgroups differed (i.e., some used the relative SMR, the risk compared with the general population in each group, and some used an IRR directly comparing the incident rate in two groups; see Table 115)

e

No multivariate regression analysis

f

In the Stern cohort, after 1984 the numbers remaining in the follow-up assessments were <80%. However, the majority of this attrition was due to death at rate consistent with that expected in the general population. Withdrawal and loss-to-follow-up for reasons other than death was at an acceptable level considering the long-term nature of the study (<20% lost by 2001, 25 years after recruitment). However, the reasons for loss to follow-up were unclear and it cannot be determined whether the characteristics of those who withdrew from the study or were lost to follow-up were different from those who remained and could have skewed the results.

g

It is unclear whether the threshold for stratification in PUVA dose subgroup analyses was pre-specified or chosen based on the data, which could lead to bias

h

Those who received retinoids and were included in this study had higher PUVA exposure among than the average for the full cohort

i

This study has prospective and retrospective elements to its design

j

All eligible individuals were included in the study but some data were missing and so were imputed

From: 9, Phototherapy

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