Sickle cell disease: a solubility test could accurately diagnose sickle cell trait or disease.

Clinical bottom line (level 4)

A haemoglobin solubility test could accurately diagnose patients with sickle cell trait or disease.
A negative test made sickle cell trait or disease very unlikely.

Greenberg et al: New England Journal of Medicine 1972; 296 (21): 1143-1144

Expires July 2004

The study

Setting: university hospital, USA

133 patients (aged ?, ?% male) being screened for sickle cell trait

Independent unblinded reference standard, applied in ?all patients from a ?consecutive appropriate spectrum.
Reference standard:

sickling on sodium metabisulphite test and haemoglobin electrophoresis

Diagnostic test: sickling reagent (potassium hydrophosphate and potassium dihydrophosphate): positive if after 3 minutes, tube is opaque (observer unable to see black newsprint through the solution).

The evidence

diagnostic test	sickle cell trait	no sickle cell trait	LR+ (95% CI)	post-test probability	LR- (95% CI)	post-test probability
solubility test	33	0	- (32 to infinity)	100%	0.0 (0.00 to 0.25)	0%
total	33	100

Comments

Post-test probabilities are meaningless in a preselected group. However roughly 8% of Africans have sickle cell trait - this has been used to calculate the post-test probabilities.
A SpPin test! (if positive it rules the disorder in).

Citation

Greenberg MS, Harvey HA, Morgan C: a simple and inexpensive screening test for sickle hemoglobin. New England Journal of Medicine 1972; 296 (21): 1143-1144

Contributor: Chris Ball and Clare Wotton, July 1999
Reviewer:

_{Clinical Question.}

_Patient	_African
_{Intervention or Exposure}	_{solubility test}
_Outcome	_{sickle cell trait}