Screening for peripheral neuropathy and peripheral arterial disease in persons with diabetes mellitus in a Nigerian University Teaching Hospital


This is a descriptive Study carried out at the Diabetes Clinic of the Lagos State
University Teaching Hospital (LASUTH), Ikeja, Nigeria. This is a 750 bed hospital
upgraded in 2001 from a General Hospital to a teaching hospital. It is located in
the capital of Lagos State with highly subsidized health care costs as a result of
governmental policy.

Consenting patients were recruited consecutively over a 3-month period. All persons
living with DM aged more than 20 years and who had no past histories of foot ulceration,
were recruited into the study. Ethical approval was obtained from the Lagos State
University Teaching Hospital.

Demography validated interviewer administered questionnaires were used to obtain histories pertaining
to clinical characteristics of DM status and complications of neuropathy and PAD,
smoking, alcohol and co-morbidities such as hypertension. Long duration of DM means
10 years and older age referred to 60 years.

The anthropometric indices measured included waist circumference, height and body
weight, and the body mass index (BMI) in weight/height
2
(kg/m
2
). Waist circumference was determined by applying a tape measure to the midpoint between
the inferior margin of the last rib and the crest of the ilium. The blood pressure
was measured both in supine and upright positions.

A biothesiometer was used to determine semi quantitatively vibration perception thresholds
in a standardized manner by a single observer. The biothesiometer probe, which vibrates
at an amplitude proportional to the square of the applied voltage, was applied perpendicularly
to the test site with a constant and firm pressure. Subjects were initially familiarized
with the sensation by holding the probe against the distal palmar surface of hand.
VPT was then measured at the distal plantar surface of great toe of both the legs.
The voltage was slowly increased at the rate of 1 mV/sec and the VPT value was defined
as the voltage level when the subject indicated that he or she first felt the vibration
sense.

DM Neuropathy referred to a vibration perception threshold values of more than 15 mV
with or without the presence of neuropathic symptoms 7].

A hand held Doppler equipment with a frequency of 12 MHz was used to document the
ABI. The ABI was performed by measuring the systolic blood pressure from both brachial
arteries and from both the dorsalis pedis and posterior tibial arteries after the
patient has been at rest in the supine position for 10 min. We used a standard blood
pressure cuff at the ankle. We began recording the pressures with the right arm, then
the right leg, then the left leg, and finally the left arm.

The higher systolic blood pressure value was used as the numerator of the ABI in each
limb. (An ABI of 1.30 denoted incompressibility of the vessels and persons with such
readings were excluded from the analyses). The diagnostic criteria for PAD based on
the ABI were interpreted as follows:

Normal if 0.91–1.30, Mild obstruction if 0.70–0.90, Moderate obstruction if 0.40–0.69,
Severe obstruction if 0.40, Poorly compressible if 1.30 8].

HbA1c was assayed using a fully automated Boronate Affinity assay for the determination
of the percentage of hemoglobin A1C (HbA1c %) in whole blood. Poor glycaemic control
consisted of glycosylated hemoglobin (Hba1c) levels of ?7 % 9].

Hypertension was said to be present in persons known to have a history of elevated
blood.

Fasting blood samples were taken for the determination of four parameters of the lipid
profile viz total cholesterol (TCHOL), high density lipoprotein cholesterol (HDL-C),
and triglyceride (TG). Total cholesterol assay was done using a modified method of
Liebermann-Burchard, HDL-cholesterol by precipitation method and TG was estimated
using a kit employing enzymatic hydrolysis of TG with lipases 10]. LDL-C was calculated using the Friedwald’s formula 10] LDL = (TCHOL ? HDL-C) ? TG/5 when the values of TG were less than 400 mg %. Abnormal
lipid profile consisted of the following abnormalities either singly or in combination;
triglyceride (TG) levels ?150 mg %, high density lipoprotein cholesterol (HDL-C) (for
men ?40 mg % and women ?50 mg %), low density lipoprotein cholesterol (LDL-C) ?100 mg %
10].

Statistical analyses were performed with SPSS version 15. A multiple regression analysis
with PAD as the dependent variable in conjunction with multiple independent variables
was used to evaluate for possible predictors of PAD. Independent sample Student’s
t test was used to compare quantitative data. ?
2
was used to test for differences in proportions. A p value of ?0.05 was deemed significant.