Study design

This was a comparative cross-sectional study that involved comparing 52 women diagnosed with PCOS and insulin resistance to 96 women diagnosed with PCOS without insulin resistance. All participants provided written informed consent and completed a semi-structured questionnaire. Blood samples were collected and analyzed for levels of fasting blood glucose, fasting insulin, and serum adiponectin.

Study area and population

The study took place at Lagos State University Teaching Hospital Ikeja and Lagos Island Maternity Hospital, Lagos. It included women of reproductive age who had been diagnosed with PCOS according to the Rotterdam criteria in the Gynecology Clinics at the aforementioned hospitals.

Sampling

Convenience sampling was utilized to recruit consenting women with PCOS who attended clinic days at both hospitals consecutively until the desired sample size was achieved. The study spanned a period of 2 years (January 21, 2020, to January 20, 2022). Participants were categorized into two groups: those with PCOS and insulin resistance as cases, and those with PCOS without insulin resistance as controls.

Sample size estimation

The sample size formula for comparative study was used in calculating the sample size [19]. The formula being as follows:

$$}\,} } \frac} }\left( }^}}} \right) \left( }}^}}} \right)}\beta } }\alpha )}^}}}}}_}}} }_}}} \right)}^}}}}}$$

r – Ratio of control to cases, this was taken as 1.

Px – the average proportion of PCOS with IR (exposed cases) + proportion of control (PCOS without IR)/ 2.

Zβ– Standard normal variant for power which is 1.28 and 0.8 for 90% and 80% power respectively (1.28 for 90% power will be used).

Zα– Standard normal variant for level of significance = 1.96.

P1 – P2 = Effect size of difference in proportion expected based on previous studies. P1 is the expected proportion in study group based on maximum available proportion from previous studies while P2 is the proportion in control based on maximum available proportion from previous studies [20].

$$\begin}\,}}\,\left( }} \right)\\}\,}}\,\left( }} \right)\\}\,}\,}\frac}\left( }}\,}}} \right)\left( }\left( }}}} \right)}} \right)}}\,}} \right)}^}}}}}}}} \right)}^}}}}\\}\frac}\left( }}} \right)\left( }}} \right)\left( }}} \right)}}}}}}\\}\,\frac}\,\left( }}\,}\,}}} \right)}}}}} \right)}^}}}}\\}\,\frac}\,}\,}}}}}}}}\,\,\,\,\,\,}\end$$

With the attrition rate of 10%, the minimum sample size for this study was 74 (67 + 7) participants per group as 10% [7] of the samples size was added to the ‘calculated sample size’ to account for the non-response rate. So, the total sample size for this study was calculated to be 148.

Data collection

Participation in the study was contingent upon obtaining written consent from women. Recruitment was conducted consecutively until the predetermined sample size was reached. Following eligibility confirmation, participants were situated in a quiet environment ensuring individual privacy. A semi-structured questionnaire was utilized to gather baseline demographic data and reproductive characteristics. For participants with no education, the questionnaire was administered by the researcher, while others self-administered it.

Specimen collection

At the second gynaecology clinic visit where participants came for in a fasting state, blood samples were taken. Ten millilitres of blood were collected aseptically from the antecubital fossa vein with minimal stasis using pyrogen free disposable needles and syringes. Five millilitres of the blood were put into two separate labelled specimen tubes each: a Serum Separator Gel tube for the Serum Adiponectin and Serum Fasting Insulin assay and a Fluoride Oxalate tube for the Fasting Plasma Glucose assay. These specimen tubes were transported to the laboratory within 1 to 2 h of specimen collection where they were stored at -200C till analysed within 72 h.

Specimen analysisSerum adiponectin

Serum Adiponectin was assayed using a solid phase enzyme-linked immunosorbent assay. The assay was done using Abcam’s Human Adiponectin ELISA kit which measures the quantity of adiponectin in serum.

Fasting serum insulin

Fasting serum Insulin was assayed using a solid phase enzyme-linked immunosorbent assay. The assay was done using the Accu-Bind ELISA Microwells manufactured by Monobind Inc, USA.

Fasting plasma glucose

Fasting plasma glucose was assayed using Glucose Mono Reagent (Glucose Oxidase/Peroxidase method) manufactured by Atlas Medical, United Kingdom.

Determination of insulin resistance (IR)

Insulin Resistance was determined in all the study participants using the Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) which was calculated as;

$$\beginHOMA - IR = fasting\,insulin\,(\mu U/ml)\, \times \,\\fasting\,glucose\,(mmol/l)/22.5\left( \right).\end$$

A HOMA-IR value of > 2 was considered as Insulin Resistance for this study [12].

HOMA-IR value of ≤ 2 was considered without Insulin Resistance in this study.

Data analysis

The SPSS version 22 was used for data entry, validation and analysis. Frequency tables was generated for all the categorical variables. To test for association between categorical variables in contingency tables, the chi-square test was used with p-values of less than 0.05 taken as significant. Multivariate regression analysis was used to evaluate for an association between serum adinopectin levels and insuline resistance in PCOS.