**3. Methodology**

Following ethical approval and informed consent from the participants, 20 subjects from each group of HIV, tuberculosis, diabetes mellitus, hypertension, schizophrenia, and dementia were recruited based on the study's inclusion and exclusion criteria. The study group comprised patients already diagnosed by the consultant physicians at their respective specialty clinics at the University of Port Harcourt Teaching Hospital and on treatment and have been regular on follow-up at their respective outpatient clinics. Participants were recruited through a simple random sampling. Those recruited were within 30–40 years of age, whose illness duration was within 3–5 years. Thirty-five normal individuals (five for each medical condition) were selected also via simple random sampling from among staff of the hospital, matched for age and sex, as controls.

Both subjects and controls were administered the study's instruments including the sociodemographic/clinical questionnaire, WHO Composite International Diagnostic Interview (WHO CIDI), and the WHOQOL-Bref. The data were analyzed using the SPSS version 20 statistical package. The cohorts and control were followed up for clinic attendance, dropout, quality of life, death, and survival rates after 5 years. Confidence interval was set at 95%, while P-value of less than 0.05 was considered statistically significant (**Tables 1** and **2**).

*Impact of Chronic Medical and Neuropsychiatric Illnesses on Quality of Life and Life… DOI: http://dx.doi.org/10.5772/intechopen.90756*
