Symptom scores and clinical measures in benign prostatic hyperplasia

Table 6 Exploratory subgroup analysis by geographic region and sample size: Pooled correlation coefficients across all three meta-analyses

Meta-analysis	Subgroup factor	Category	k	Pooled r	95%CI	I2	Notes
IPSS-QoL	Geographic region	South Asia (India, Nepal)	3	Approximately 0.75	0.66-0.91	-	Higher upper bound; includes study with r = 0.91
		Africa (Nigeria, Ghana)	2	Approximately 0.65	0.54-0.76	-	Numerically lower; both estimates are still large-effect
	Sample size	Large (n > 100)	4	Approximately 0.68	0.54-0.76	-	More stable; consistent effect
		Small (n ≤ 100)	1	0.910	-	N/A	Single study[23]; interpret with caution
PV-IPSS	Geographic region	Africa (Nigeria, Cameroon)	3	0.22	0.01-0.41	-	Substantially lower; storage-symptom dominance
		South/Southeast Asia (India, Bangladesh, Indonesia)	6	0.52	0.35-0.66	-	Consistent moderate-to-large effect
		Pakistan	3	0.51	0.32-0.66	-	Comparable to South/Southeast Asia
	Sample size	Small (n < 100)	5	0.44	0.22-0.63	-	Wider CI; includes influential study[29]
		Large (n ≥ 100)	7	0.46	0.30-0.61	-	More stable and representative
IPSS-PVR	Geographic Region	Africa (Nigeria, Ghana, Cameroon)	6	0.262	0.079-0.425	54.3%	Moderate heterogeneity within subgroup
		Pakistan	2	0.738	0.461-0.882	High	Only k = 2; tertiary referral bias likely
		East Asia (Korea)	1	0.200	0.090-0.305	N/A	Single study[31]
		Western (United States, Turkey)	2	0.220	0.121-0.313	Low	Earlier disease detection; diverse LUTS aetiology
	Sample Size	Large (n > 200)	4	0.178	0.094-0.259	31.2%	Large, representative samples; more conservative
		Small (n ≤ 200)	7	0.446	0.261-0.604	68.1%	Small-study effect; higher and more variable estimates

k: Number of studies in subgroup; Pooled r: Back-transformed correlation from variance-weighted random-effects pooling (τ² carried from full model); 95% confidence interval on r scale; I²: Within-subgroup heterogeneity. Subgroup analyses are exploratory; formal between-subgroup Q-tests were unavailable for all analyses. -: Insufficient k for meaningful I² estimation. Subgroup estimates should be interpreted with caution, given the small k per subgroup. An omnibus between-subgroup Q-test was not generated by the variance-weighted pooling procedure; however, the principal pre-specified regional contrast (Africa vs South/Southeast Asia for Prostate volume-International Prostate Symptom Score) was tested formally on Fisher’s Z scale and was statistically significant (Z = 2.29, P = 0.022).

IPSS-QoL: International Prostate Symptom Score-quality of life; PV-IPSS: Prostate volume-International Prostate Symptom Score; IPSS-PVR: International Prostate Symptom Score-post-void residual; CI: Confidence interval.